Seinfeld

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.

If you can't get Jerry Seinfeld to do it, who better to judge someone's Seinfeld impression than the man who played his best friend for nine seasons ... Jason Alexander.

Not only did Alexander tolerate our photog's attempt to do Jerry outside Spago yesterday in Beverly Hills, but the man best known for playing George Costanza even gave our guy a handful of constructive feedback ... and gave him a pretty good overall rating.

It's one of the most iconic scenes in "Seinfeld" history -- the parody of the magic bullet scene from "JFK" -- but the question is ... has Oliver Stone seen it?

Almost a week after "Seinfeld" star Daniel Von Bargen attempted suicide by shooting himself in the head, an episode of the show entitled "The Suicide" -- during which Jerry Seinfeld jokes about people who try and commit suicide, but fail (see above) -- aired on TBS.

The episode originally aired in 1992 and Von Bargen, who played Mr. Kruger, didn't begin his stint on the show until years later. The episode aired again last night. TBS had no comment.

So we gotta ask ...

As TMZ first reported, Alexander was involved in a car vs. bike collision in L.A. back in April -- cops quickly determined that Jason was not at fault.

Richards even signed a few autographs on the way out of the show -- including one for a guy in a BET shirt ... who happened to be white.

Still, progress is progress.

Richards made light of the rant on this weekend's episode of "Curb Your Enthusiasm." During one of the scenes, Richards -- playing himself -- blows his top at an African-American character, saying, "If only there were a horrible name that I could call you ... that would make you as angry as I am."

A group of spectators who witness the tirade instantly whip out their cell phones and begin to record. Richards, realizing the similarity of events, screams and bolts.

Couple of problems here: First off, the original tirade was shot on a DIGITAL CAMERA -- not a cell phone.

Second: Is Richards mocking himself ... or the digital-recording culture that exposed his greatest mistake? In other words, is Richards and "Curb" trying to make a bad joke out of a serious situation?

Kramer was all smiles when we saw him last night in NYC, and why not? He was just on the cover of Entertainment Weekly and is reuniting with his old "Seinfeld" pals on an episode of "Curb Your Enthusiasm."

These could be the first steps out of that deep, dark black hole his career has been in for the last three years -- so we gotta ask ...

A lawsuit claiming Jerry Seinfeld's wife, Jessica, stole the idea for her best-selling cookbook was tossed out by a Federal judge yesterday.

A woman named Missy Chase Lapine sued the Seinfelds claiming they took her idea for a cookbook about sneaking healthy foods into kids' meals.

TMZ caught Britney out at Ralph's grocery store last night where she told us that pregnancy test she was holding in photos seen yesterday wasn't for her -- but for "a friend." Do her other personalities count as friends?

Later on, Brit went to the trendy clothing shop Kitson -- at 1:30 AM! She had the owner of the store, Fraser Ross, open it up just for her. She walked in wearing a short red dress, but walked out with a dress shirt and tie thrown on top.

But the ripped stockings were a nice touch.

A Pennsylvania couple is suing Martha Stewart Living and K-Mart, claiming the domestic diva's "Everyday" dinnerware -- with the lovely name "Flowers and Buds Border" -- contains lead and is responsible for poisoning their children. Get the lead out!

In the lawsuit, filed on behalf of their two kids Michael and Matthew, Sandra and Raymond Dombroski allege the boys were poisoned by lead in the dinnerware, which caused the boys to suffer "mental, emotional and cognitive impairment, learning disability" as well as speech problems and physical impairment and a host of other problems. That's not a good thing!

The Dombroskis say that the lead problem is a result of "negligent, reckless, intentional and outrageous conduct of MSLO..." (that's Martha Stewart Living Omnimedia), and they've served up a heaping lawsuit asking for compensatory and punitive damages.

A spokesperson for MSLO told TMZ "We take consumer product safety very seriously. We do not comment on pending litigation."

Damon Wayans became the first famous offender of the Laugh Factory's ban on the use of the n-word, and was fined and banned from the club for three months as a result, Wayans' publicist tells TMZ.

After the Michael Richards incident on November 17, the club decided to ban use of the word and fine comedians $20 for every offense. Wayans took the stage Sunday during a showcase of African-American comedians called "Chocolate Sundaes." Wayans opened his routine with the line, "Give yourselves a big round of applause for coming down and supporting 'N***** Night.'" According to the L.A. Times, Wayans used the word 15 more times during his 20-minute appearance.

That's a $320 contribution to the Laugh Factory's swear jar. Wayans' rep had no further comment other than to confirm the fine and the temporary ban.