Comedy Central

Barack Obama made, arguably, the best decision of his presidency when he jacked a "Key & Peele" skit for his standout moment at the White House Correspondents Dinner.

If you missed it -- 'cause like most Americans, you don't watch CNN or C-Span on Saturday nights -- the prez brought out 'K&P' star Keegan-Michael Key to play his "anger translator" ... who says what POTUS is really thinking during speeches.

The bit always killed ... like it always does. Check out the pot shots at the media (including the W.H. Correspondents), Ted Cruz, and even Hillary Clinton.

Ralphie May thinks non-comedians like Ludacris should leave comedy to the professionals, because Ralphie's indignant at Luda's indignation over that Paul Walker joke during the Justin Bieber roast.

Our photog got Ralphie at LAX Friday and he made no bones about it. He thinks Luda's a "bad sport" for going ballistic when Jeff Ross cracked, "Move Bitch, get out of the way, is what Paul Walker should have told that tree."

The comedians at the Justin Bieber Roast crossed the line when they used the death of Paul Walker to mock the roastee ... so says Comedy Central which is cutting the jokes from the show.

Jeff Ross mocked Bieber, comparing his driving skills to Paul Walker's and then referenced Ludacris' song, "Move Bitch," saying, "Move bitch, get out of the way, is what Paul Walker should've told that tree. Too soon? Too fast? Too furious?"

Apparently the joke royally pissed off Luda and Bieber didn't like it either.

Comedy Central said the joke crossed the line and it will be 86'd from the show.

He's burned Kobe ... He's burned Barkley ... and now Shaquille O'Neal has his sights on Justin Bieber -- 'cause he's been tapped to be an official flamethrower at the Comedy Central Roast.

Shaq -- along with stars like Snoop Dogg, Ludacris, Jeff Ross and Martha Stewart (what?!) -- will be tasked with ripping the Biebs to shreds in front of a packed house on March 30th.

Shaq and Bieber have history -- they once had a dance battle back before Bieber turned heel.

Comedy Central is pulling out the big guns for Justin Bieber's roast ... and we've learned two comedians who don't hold back have signed on.

Sources involved in the roast tell TMZ ... the network has locked down both Jeff Ross and Hannibal Buress for the big show next month. You'll recall, Ross has already said he was ready to destroy.

As for Buress ... well, you can ask Bill Cosby about that.

Kevin Hart will officiate as Roast Master, and there are some huge names producers are now gunning to get.

Never say never Justin ... about backing out.

Jon Stewart is leaving "The Daily Show" after nearly 20 years as a correspondent and anchor.

Comedy Central just announced Stewart would wrap up his duties on their hugely successful show later in 2015. There's been a lot of speculation about whether he would continue on the show when his contract ended this year.

Stewart talked about his decision in November on "The Howard Stern Show."

Stewart took over as host in 1999 ... and under his lead "The Daily Show" won the Emmy for Best Variety Series every year from 2002 to 2012. All told it's won 18 Emmys.

Comedy Central did not give a specific date for Stewart's last day on the air.

Justin Bieber's heartfelt video about changing his ways might melt the hearts of Beliebers, but comedian Jeff Ross could care less -- he's still gonna rip him to shreds at the roast.

The Roastmaster General was just getting back to L.A. -- fresh off roasting Terry Bradshaw at the Super Bowl -- when we asked him about Justin begging for forgiveness for all his d-bag antics.

Let's just say Jeff seems unmoved.

As for what's off limits during Bieber's upcoming Comedy Central Roast ... Ross had a pretty surprising response -- especially considering JB's checkered past.

Watch this ... you can almost see Ross licking his chops.

Justin Bieber ASKED to be skewered by Comedy Central because he wants to make a public declaration he's screwed up a lot in the past, but he's figured it out and has changed for the better.

TMZ first reported ... Justin himself asked to be roasted to celebrate his 21st birthday. We're told he views it as a form of therapy ... acknowledging hijinks from DUIs to pissing in kitchen buckets.

But here's the thing ... Justin definitely seems to have changed over the last 4 months. People around L.A. tell us he's polite again, respectful and extremely generous. He went to Mozza in L.A. Sunday night but the restaurant was full. Two guys saw him and gladly moved to the bar so he could have a table. We're told Justin walked up to thank them and then bought their dinner.

And Justin was in line at a restaurant a few days back and randomly bought a meal for some people behind him.

People who have regular contact with Bieber tell us they've seen a radical change. As one put it, "The person I knew is back."

As for why the roast will be therapy ... we're told Justin thinks the evening will end the chapter of his life where he messed up. He'll take his lumps, and then move on as a real adult.

John Pinette -- best known for his role as the fat guy who got mugged in the "Seinfeld" finale -- has checked himself into rehab after becoming addicted to prescription medication ... TMZ has learned.

A rep for the venue in Canada where John was set to perform in next month says Pinette had to postpone the gig because he was checking into a rehab facility for his addiction.

The rep says John -- who also had his own Comedy Central special in 2011 -- underwent surgery earlier this year and got hooked to the prescription medication he was taking.

John has since tweeted to his fans about the situation -- saying, "Thanks to everyone for your concern and well wishes.. Want to apologize for having missed shows last weekend, but I hope you understand!"

In case you're not a "Seinfeld" fan (WHAT'S WRONG WITH YOU?!?) ... Here's his famous scene from the super disappointing finale.

At least the reunion on "Curb Your Enthusiasm" kinda-sorta-not-really made up for it.

Amy Schumer wants Method Man to Wu her Tang ... seriously.

The Comedy Central star was at LAX recently -- where she seemed shocked by her meteoric surge in fame -- but still took time to talk to TMZ about vaginal homicide ... a la Amanda Bynes.

We should have known by Lindsay Lohan's SNL performance that she has no sense of humor ... but this really takes the cake -- celebrity roastmaster Jeff Ross says Lindsay REFUSES to participate in this year's Comedy Central Roast.

It would've been a great idea to let comics poke fun at her fresh out of rehab ... because if there's anything we can learn from Alec Baldwin, it's that comedy can defuse almost any kind of negative publicity.

Wayne Brady says he takes "full responsibility" for using Trig Palin and his Down Syndrome as a punchline at the "Comedy Central Roast of Roseanne" ... insisting "no malice or harm was meant."

Brady has been taking some serious heat for the past week ... over a joke in which he says Sarah Palin hates Jeff Ross because he reminds her of "what Trig is going to look like when he's 40."

Wayne issued a statement on Facebook in which he says he didn't write the Jeff joke but explains, "At the end of the day I take full responsibility for saying it."

He adds, "I could defend it as a performer, but I would rather apologize from the bottom of my heart as a father."

"To the Palins, please know that no malice or harm was meant. To the other families who were touched negatively, I hope you'll be able to accept this apology as well."

Brady was at LAX this weekend ... and told us, "It's a roast, but there are people with sensitivities ... and some people were bothered."

File this under "Things You Didn't Expect to Hear Today" -- Wayne Brady is under fire for a RACY joke he made at the "Comedy Central Roast of Roseanne" .... WAYNE BRADY!!!

So what subject was so touchy that the crowd actually booed?? Brady made a joke featuring Sarah Palin's son Trig ... who suffers from Down Syndrome.

Now for the joke ... which Brady made while addressing Jeff Ross:

"Now the thing is Jeff ... these are all jokes, and I really like you. I really, really like you. But a lot of people hate you, especially Sarah Palin because you remind her of what Trig is going to look like when he’s 40."

After years of HATING EACH OTHER'S GUTS -- Tom Arnold says he made a last minute appearance at Comedy Central's roast of Roseanne last weekend ... to bury the hatchet once and for all.

TMZ broke the story ... A few weeks ago Tom was adamant he wanted nothing to do with the CC bash ... not surprising since he and Rosey had a notoriously nasty split back in 1994.

But a producer for the show tells TMZ ... Tom initially turned down his invitation to participate in the "Roast" ... but had a change of heart at the very last second and contacted producers to let them know he changed his mind.

We're told producers were on board, but had to get the green light from Roseanne first ... and in another shocking turn of events, she said yes.

The best part ... we're told after Tom roasted her, the pair shared a private moment backstage for the FIRST TIME IN 17 YEARS.

In case you're curious, here's one of Tom's "jokes" that helped settle their long-time beef:

"She may not be the perfect wife, but she is literally the worst f-ing EX-WIFE on the planet ... trust me."

Comedy Central is censoring Jeff Ross ... refusing to air the jokes he made about the "Dark Knight Rises" massacre during this weekend's taping of the "Comedy Central Roast of Roseanne."

Ross -- who came to the event dressed like Joe Paterno, accompanied by two young topless boys -- has been under fire for cracking the following zinger, directed at Seth Green:

“Seth, congratulations. This is actually a great night for you ... you haven’t gotten this much attention since you shot all those people in Aurora. ... I’m kidding. You are not like James Holmes. At least he did something in a movie theater that people remember!”

Comedian Jeffrey Ross made quite an entrance to the Comedy Central Roast of Roseanne Barr last night ... dressing up as legendary Penn State football coach Joe Paterno and walking the red carpet with two very young looking males wearing nothing but towels.