Season 9, Episode 21: "The Clip Show"

Could it be because you don't want him to know...

...you have a friend who pees in the shower?

-No, that's not it. -Oh, I think it is.

-That's exactly what it is! -Why couldn't you wait?

I was there! I saw a drain!

Since when is a drain a toilet?

It's all pipes! What's the difference?

Different pipes go to different places.