Trap Button

When the belly button rule fails because she is an "outie."

Patrick: Cheryl had me go down on her, but I puked when I caught a whiff of her trap button.

Dustin: What the fuck is a trap button?

Patrick: It's when you can't tell she's a whore because she's an "outie" and never wears clothing that exposes her belly. You think it's kosher until you're south of the border.