There’s a Gary Larson cartoon (with which most of this group will probably be familiar) showing a caveman pointing to the spiky clump at the end of a stegosaur’s tail and saying, “Now this end is called the thagomizer, after the late Thag Simmons.”

The spiky clump on stegasaur tails is formally referred to by paleontologists as the “Thagomizer.”

Wikipedia entry, Palaeos entry, etc., etc.

(via LawDog)