A prank where a male slides his penis through the hole in a donut, then runs around his office asking if anyone wants a bite of his donut.
SALLY: I wonder where Bob is?
TOM: I think he went in the kitchen.
BOB: Does anyone want a bite of my donut?
SALLY: Oh, Bob, you're such a cutie.
TOM: I can't believe I fell for the old "Donut Fucker"