Boogie Woogie Bugle Boy of Company 'B' (1941)

Hot Breath Harry is a hot trumpeter at a jazz club. He finds himself drafted into the Army, where he's assigned to be the bugler of an African-American company. But everyone hates the bugler, because he blows reveille at the ungodly hour of 5 AM sharp. Sure enough, on his first day, Harry gets pelted with everything imaginable. He lands against a wall, where his trumpet falls on him. He plays a swinging wakeup that segues into the title tune, and nobody minds waking up to this. Everyone swings through the whole day, even when three soldiers march into a lake and two soldiers, followed by a grinning alligator, march out.