Something which people are often out of.
Donny: What the fuck is he talking about?
The Dude: My rug.
Walter Sobchak: Forget it, Donny, you're out of your element!
The act of performing oral sex on an elderly woman.
Disgusted Roommate: "I walked in on Gary doily diving again. I told him if he doesn't stop, I'm kicking him out."