/wa-bət/
[almost certainly from Elmer Fudd's immortal line "You wascawwy wabbit!"]
n. 1. A legendary early hack reported on a System/360 at RPI and elsewhere around 1978. The program would make two copies of itself every time it was run, eventually crashing the system.
2. By extension, any hack that includes infinite self-replication but is not a virus or worm.
See also cookie monster.