Here's one I'd like to have :
Si hoc adfixum in obicle legere potes, et liberaliter educatus et nimis propinquus ades.
(If you can read this bumper sticker, you are both very well educated and much too close.}
And a good one for personnel managers:
Si hoc signum legere potes, operis boni in rebus Latinus alacribus et fructuosis potiri potes!
(If you can read this sign, you can get a good job in the fast-paced, high-paying world of Latin!)
And just for the heck of it here are a few more I've collected :
Sona si Latine loqueris.
Honk if you speak Latin.
Catapultam habeo. Nisi pecuniam omnem mihi dabis, ad caput tuum saxum immane mittam.
(I have a catapult. Give me all the money, or I will fling an enormous rock at your head.)
And, finally, here's one for the Golf Widows :
Braccae illae virides cum subucula rosea et tunica Caledonia-quam elenganter concinnatur!
Those green pants go so well with that pink shirt and the plaid jacket!
