Vanity plates are 99% ridiculous. Most of the time your 'clever, concise and witty' saying is not going to get your point across effectively.
For instance: A HS german teacher in my hometown had a vanity plate wishing people 'good day' in german.
The most common comment on the family's ride was 'We love hunting, too!', followed closely by 'do you work for fish and game?'
The license plate read 'GUTNTAG'.
If you really want people to know you are a pool player, buy a 1992 caprice, fill it up with fastfood wrappers, shred the seats, repair those same tears with duct tape and leave a broken moochi in the rear window.
THAT says 'pool player' better than any seven letters in all caps.
dld