Mad-Shagger
A person who's always getting it on with their partner, even when they're both too tired to move.
My parents are mad-shiggers. They have sex at 3 a. m. and wake me up with loud moans.
My brother's girlfriend is a mad-shagger. They have sex in the car, on the couch, and once in the grocery store.
My neighbor is a mad-shagger. I heard them screaming at 2 a. m. over a broken toothpick.