Brooke Mueller got into it Tuesday with the crew of a United jet from L.A. to Cancun, and it's unclear if she was removed from the plane or just got off in a huff.
Sources close to Brooke tell TMZ ... just before the plane was about to push back from the gate, Brooke felt nauseous and said she needed to go to the bathroom. The flight attendant told her she could not get up, and things then got heated.
Brooke insisted she had to throw up, but Brooke is telling people the flight attendant rudely replied, "Tough." Brooke then went ballistic and demanded to get off the plane. She says her wish was granted.
But a witness on the plane tells TMZ ... Brooke was "belligerent and cussing out the flight attendant" so she was removed from the plane.