To have sex TONS of times a day. Comes from the fact that bunnies reproduce at a more rapid rate than humans, and therefore they have lots of sex. This style of fucking can be found among sexaholics, and particularly among horny college students.
Person 1: Hey, I haven't seen Julia and Dan all day. Have you?
Person 2: No, but I can hear them having crazy sex from my dorm room.
Person 1: They're still going at it?!?
Person 2: Yeah, this must be the 7th time today. They have sex like bunnies.