MTO SUPER WORLDWIDE EXCLUSIVE: R&B Singer Chris Brown . . . Appears To Be DOING DRUGS . . . At Tyga’s Son’s BIRTHDAY PARTY . . . While His DAUGHTER Is There!! (We Got EXCLUSIVE Pics)

 

MediaTakeOut.com OBTAINED EXCLUSIVE FOOTAGE which appears to show Chris Brown - sippin' lean with his friends . . . while at Tyga's son Cairo's birthday party. Chris attended the party with his own ONE-YEAR-OLD daughter Royalty.
 

Chris is in the midst of a fragile child custody arrangement with his child's mother. She initially REFUSED to allow Chris to have joint custody - because she worried about his DRUG USE. Chris eventually got her to agree to JOINT CUSTODY.

Well these new images might have her thinking twice. The video shows Chris Brown's homies OUTSIDE of Tyga's party - clearly they are sippin LEAN. It's not clear whether Chris is TOO . . . but he has a DOUBLE CUP with a mystery liquid inside it.

When Chris realized that the PAPARAZZI was around, he drove off.