Bingowings said:

Another usable sample this time from Superman 2 are the lines :

LEX LUTHOR : Why didn't you go before we left?

MISS TESCHMACHER : That was two days ago.

Ok, I think it may have finally sunk in. I take it "go" means potty-time.

I thought it was "go" as in "leave." I haven't seen Superman 2 in a long time.

JEDIT: The problem here, and to a lesser extent with the MST3K idea, is that it won't be clear where the voices are coming from. Not that it has to be clear, but it could be confusing.