A custom made coat that is used to keep a man's scrotum warm. The coat is typically made from worsted wool or cashmere. Few companies use polyester because it can be very hot and leave chaffing on the actual nut skin.
Jeff: Hey Rocky! Did you hear that Wal-Mart is now carrying coatums?
Rocky: No Jeff I didn't, did you buy one?
Jeff: Yeah man! Mine is made out of cashmere..
Rocky: Sweet dude!! Can i try it on??
Jeff: Fuck you man! Get your own.
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.