1. A small (15-25 lb) street mongrel common to the California-Baja border. Part Chihuahua, part terrier (or other small breed), resourceful, crafty, and totally lacking in loyalty, the dog survives using his wits and charm.
2. A shifty vagabond who survives using wits and charm.
Q: Should we ask that man for directions to the cantina?
A: No, not him -- he looks like a Tijuana Terrier.