Mambo from West Side Story has always been my favorite, quickly followed by Rich Man's Frug from Sweet Charity. But recently, I'm Alive from Tootsie. The music is head-bopping infectious (it makes me want to frug and pony all over the place) and the choreography is hysterical.
"What can you expect from a bunch of seitan worshippers?" - Reginald Tresilian