Tom in the Iron Butt
The Iron Butt is a machine that doctors in Bikini Bottom use if a patient's butt is badly injured. Tom had to use one at one point in his life. This device was only mentioned and shown in one episode, "I Had an Accident". The Iron Butt is a parody of a device called the Iron Lung, which is used for breathing problems with Polio. SpongeBob fears them.