(n): myu-sih-kil thee-ter A form of theatre incorporating singing and dancing in addition to acting. It is often criticized for having characters break out into song and dance in the middle of an intense moment. Males who participate in it are also the butt of many a homosexual joke. The creators of such jokes tend to be jocks whose girlfriends made out with the leads in school musicals onstage in front of over one thousand people while they just sat squirming in their seats wishing they were the one up there.
Jock: Hey, faggot, I hear you do Musical Theatre, want to go to skip practice and get your nails painted?
Thespian: Sorry, I can't skip today, I need to work on the kissing scene with your girlfriend. Why don't you go wrestle some sweaty half naked men?
A hobby for social outcasts who find little interest in sports or rock and roll music. Includes (but isn't limited to) dancing, singing, acting, and even sometimes gymnastics.
A: What sport do you play?
B: I do musical theatre.
A: Oh... cool. Have you seen CATS?