A nickname for a long-distance motorcyclist. The Iron Butt designation often specifically applies to someone who has motorcycled 1000 miles in a 24-hour period.
"I earned my Iron Butt patch last July when I rode from Poughkeepsie to Jacksonville in last than 24 hours."
by Bill from VA February 13, 2012
Peanut has iron butt again!
by trumpetcatz July 30, 2003