There's probably a lot of them. One that comes to mind, just because I love that episode, is "The Gum". George, whose girfriend already suspects he's gone insane, ends up walking down the sidewalk dressed up as Henry VIII. He also suspects that he was shortchanged by the cashier at Monk's because he thinks he gave her a $20, which had a lipstick doodle on it. It's all very complicated
In any case George stops to buy a pack of gum, and that's Larry at the counter, delivering the priceless line: "I beg your pardon, your majesty, but we don't accept bills with lipstick on the President."