An area of thick chest hair that is visible on a man when he is wearing a collared shirt that is not completely buttoned. Named after former Baywatch star David Hasselhoff and his well-known chest hair.
Beth: "Mike, I can see your Hasselhoff Patch!"
Mike: "Oh no - I better put on another shirt."
Jenny: "Tony, did you try shaving your Hasselhoff Patch?"
Tony: "I didn't, but that may be a good idea!"