People here who think "oh they make minimum so its never okay to tip below 15%" are way too ****ing generous as far as i'm concerned.
here's a news story, there are people working harder jobs at minimum wage that never get tipped period, if you stand there and don't hustle to give me my food, you're little to no tip. If you hustle you might get $5 tip on a $10 meal.
15% = slightly below average, 18% = slightly above average, 20% = good, 10% = awful.
If you're especially good or especially awful i might go higher than the price of my entire meal or as low as ZERO tip.
If you ****ing leave me at the table for a good hour waiting for my ****ing food or check, not only won't i tip you, i'll go get your manager and let him know how **** you are.
Meritocracy, that's how it should work.