Colin,
Yeah. But 'they' are even more restrictive about what you say :)
For instance...
I have a friend who does 'ham' radio. His federally issued call sign refers to a particular portion of a person's anatomy. The state (which issues vehicle license plates offers one for ham call signs) was not happy with his call sign and refused to issue one. After considerable time/effort my friend did get his 'vanity' plate, "W5ASS". If the 'feds' didn't think it was too suggestive, why would Texas (of all places)? :)
- 'Doc
(mine, using phonetics is "Loose Zipper".)