crusty blanket
When you're too lazy to wash your hands after masturbating and you wipe them on the edge of the blanket.
Person One: "It's getting pretty cold, mind if I borrow this blanket?"
Person Two: "No, don't use that one Mum, It's a crusty blanket"
Person Two: "No, don't use that one Mum, It's a crusty blanket"