What the Hell is a Registered Texan??

The other day while playing tourist 'West of the Brazos' noticed a sticker on the back of a vehicle in the Austin area.  Couldn't make out all of the words, but in big letters it said "Registered Texan".  That brought several thoughts bubbling up in my warped mind.  1. Do they have a breeding program in Tejas and they are registered like cattle and other livestock?? Or B. Are they on some kind of "Offender List" and in addition to having to register they have to place this sticker on their vehicle to warn people??