Anal Leap (1992)

In this spoof of the time-travelling TV show Quantum Leap, Buck plays Sam and Eric plays some guy who's a friend of his who invented a time travelling machine that had Buck accidentally sent back to the past several times. The thing is, Eric built his machine in a guest bathroom in his home and one day when Buck was visiting, he ended up flushing the toilet which triggered the machine, and wound up going back and forth to places unknown to him. Now, whenever he hears the sound of a toilet being flushed he knows his time's up and he'll be transported to another place.