Melissa McCarthy is new to the director's chair ... but she's already acting like a BOSS ... the "Bridesmaids" star just FIRED an extra for mistreating her own little kid on set ... TMZ has learned.

It happened yesterday in Wilmington, NC ... where they're filming "Tammy," a comedy McCarthy is co-directing with husband and fellow first-timer Ben Falcone.

The extra, a woman in her 20s, brought along her child -- age approximately 4-5 -- for the daylong shoot by a lake ... and the standard $58 payday ... sources tell TMZ.

Witnesses say the young mom had been struggling with her kid all morning ... constantly harping on the child to "stop it" and quiet down ... loudly enough to disrupt the production, which included more than 200 extras.

Sources say the last straw came when the mom harshly jerked the child up in the air by the wrist -- and McCarthy saw it all. The director IMMEDIATELY had PAs bounce the woman ... saying she wouldn't tolerate abuse on her set ... and that was that.

The woman's identity was not disclosed. Reps for McCarthy had no immediate comment.

Moral of the story: Don't attempt anything shady around Melissa McCarthy ... she's ALWAYS ON WATCH ...

  

7:18 AM PT -- Mystery solved ... it's a marijuana arrest.

According to the police report, obtained by TMZ, Keef was busted for allegedly smoking weed at a fancy hotel.



Chief Keef -- the 17-year-old rap sensation -- was arrested in DeKalb County, Georgia yesterday for disorderly conduct ... TMZ has learned.

The details surrounding the arrest are unclear.

According to the booking sheet, Keef -- real name Keith Cozart -- was listed at 5'9" and 160 lbs.

After the arrest, Keef tweeted, "Jus Got Out Of Dekalb County jail In Atlanta Mad As f**k."

Keef is considered a prodigy -- and has rapped with huge stars like 50 Cent and Wiz Khalifa.

Keef is no stranger to the law ... he's been arrested at least two times before -- and even has a gun conviction under his belt.

It's been a rough year for the rapper ... We broke the story, he was recently sued for child support​ by his middle-school-aged baby mama who claims Keef fathered her kid -- born in 2011 -- when he was only 15.

One day after Lindsey Vonn was spotted playing mom by dropping off his kids with Elin Nordegren at school alone, Tiger Woods joined in on the child-rearing fun.

Looking like one big happy family, Tiger and Lindsey -- who have been dating for around 5 to 6 months -- made the early morning trek to drop off his adorable children at their Palm Beach school on Tuesday.

The athletic lovebirds are really committed ... to getting those kids to class on time.

Lindsey Vonn might be in it with Tiger Woods for the long haul ... because she was spotted this morning taking his kids to school ... with no sign of Tiger.

The two awkwardly announced their relationship via Facebook back in March, saying they have "been friends for some time, but over the last few months we have become very close and are now dating."

That means their relationship is somewhere around the 5 or 6 month mark.

So, we gotta ask ...

Robin Thicke wasn't really dressed for it, but ... a bunch of high schoolers let him stand in for a photo anyway ... ON PROM NIGHT!

It went down last Saturday ... the 20 or so students from Eagle Rock High in northeast L.A. were waiting for a party bus to take them to prom when one recognized Alan Thicke's hunky pop-singer spawn shooting a music video across the street.

They called the "Blurred Lines" (No. 1 on iTunes this week!) singer over ... and he was more than happy to chill and take photos.

"He made our night!," said a student named Jesse. "When my other friends told me about their party buses, they really had nothing to say… I mean, we had Robin Thicke!”

The teens say Thicke asked if anyone wanted to appear in his video the following day ... we're told some of them took him up on it.

But probably just the goood giiiiiiiiiirls ...

Charlie Korsmo shot to stardom at a young age for his roles in movies like "Hook,"  "What About Bob" and "Dick Tracy." Guess what he looks like now!

"Modern Family" star Ariel Winter is throwing DISS after DISS at her birth mom ... making it clear, she wants NOTHING to do with her biological life-giver ever again.

As you know, 15-year-old Ariel has been at war with Chrystal Workman for the past year -- and even got a judge to strip her mother of custody in 2012 after claiming she was subjected to emotional abuse.

Now, Ariel is pouring salt in the wound -- by making public statements in which she makes it clear, her mother is dead to her ... and her older sister Shanelle has filled the emotional void.

When asked about her family yesterday, Winter told People.com, "My sister is the most amazing woman I've ever met in my life. If I could be half the woman she is ... she's kind of who I want to be like."

Did you catch the thinly veiled dig at her mom? If not, check out what she Instagrammed on Mother's Day:

"Happy Mother's Day to my amazing mister, Shanelle Gray. I know everyone is going to ask what a mister is, so I'll explain. It means mom/sister to me."

She continued, "She's my best friend ... She's also the most incredible mother. I am so blessed and lucky to have her."

Translation -- Ariel's over Chrystal ... and from what we're told, she has good reason. How's THAT for a modern family?

 

Charlie Sheen's legal team is headed for court this morning ... and he wants to expose what he believes is a crass ploy by ex-wife Brooke Mueller to make her brother the guardian of their kids so she can still get her hands on Charlie's gigantic child support checks.

As we previously reported ... Brooke is gunning to wrestle temporary custody away from Denise Richards, who has been caring for 4-year-old Bob and Max while Brooke tries to get it together at The Betty Ford Center.  Brooke wants her brother to get temporary custody until she's sober again. 

Charlie believes the almighty dollar is at the root of Brooke's ploy.  He claims Brooke will still have access to Charlie's $55,000 monthly child support check if her bro gets the kids, and that's why she wants Denise out of the picture.

What's more ... sources connected to the case tell TMZ ... Denise has written proof -- in the form of text messages -- in which Brooke makes it clear -- she wants and needs those monthly checks.

Sources say Brooke -- through her lawyer -- will counter that Denise is the one who is in it for the money, although our sources say Denise has not asked Charlie for a dime for taking Bob and Max.

We're told Charlie wants Denise to keep the twins until Brooke is sober and able to prove she'll stay that way.  Charlie realizes that could mean Denise could have the kids for a year ... and maybe longer.  Charlie will tell the judge he would gladly pay Denise support money for her efforts.

Despite all the drama in their lives, Charlie Sheen's kids with Denise Richards and Brooke Mueller really are one beautiful family.

With Denise having temporary custody over Brooke's adorable twin boys while she's in rehab at the Betty Ford Center, the children enjoyed a family outing to a fair in L.A. this weekend with Denise's dad Irv.

As TMZ reported earlier, Brooke has been trying to get her sons removed from Denise's house and placed in her brother's home because she doesn't trust Charlie (and his temper).

Adults can be such a handful.

Bug Hall is best known for playing the girl crazy Alfalfa in the 1994 remake of "The Little Rascals." Guess what he looks like now!

Brooke Mueller is making a full-court press to move her twins from Denise Richards' home to Brooke's brother's home ... because she fears Charlie Sheen's volcanic temper will put their kids in harm's way.

Sources connected with the custody war tell TMZ ... Brooke's lawyers are going to court today in an effort to remove Bob and Max, the 4-year-old twins, from Denise's home.  Brooke wants the kids to stay with her brother while she rehabs at The Betty Ford Center in Rancho Mirage.

Brooke believes Charlie is violent, and by putting the kids in Denise's care, it exposes them to Charlie.  Brooke's lawyers are going to custody court today ... to get what they claim are sealed documents outlining a pattern of violence on Charlie's part.  They want to take those documents to dependency court, where a judge stripped Brooke of custody.

Our sources say Charlie and Denise both think it's ridiculous to put the kids in the care of Brooke's bro, because he has no real relationship with the twins.  What's more, it would mean uprooting the kids from their school, doctors, family, friends, etc.

Fact is ... Denise has bailed Brooke out of these situations multiple times in the past and Charlie has helped out, so it seems weird that suddenly that arrangement is so risky.