Judging for your topic I must not be "ethnic" because I always tip, and you just said I don't. Guess I need to find out what I am. (Although come to think of it, on past occasions, others have suggested as much).

My tip is variable, from as low as 10% for shitty service to as much as 20% for excellent. I don't believe you deserve any set standard regardless of how crappy you treat the table (especially if you've approached them all shitty-like because you're thinking "gawd, i gotta wait on these ethnic types and they don't tip worth a damn" ...hint hint).

If I'm really dissatisfied (especially poor service or too long waits for food) you'll not need to worry about your tip. That's because I get up and walk the hell on out.