Mine says JAGUARS - as in the NFL team. Not funny, but in a non-football area, the comments I get are silly! One guy asked me (my car was a Mercedes) if my tag said that because I used to have a Jag, or if I wanted one... so I got one of those tag frames, with helmets, etc!
I've seen on a white Excursion, SHAMU - that was funny. We have a white Denali XL, one of the tags we ordered was GRTWHT... you have to list 3 options and they'll try to get your tag, in order of the preference you list.