The idea that we have to tip 15+% at a restaurant is pure crap. I hate feeling like I have to. no matter what. Has anybody not tipped at all at a restaurant? I'm talking about a sit down place with waiters, not Dunkin Donuts or a pizza place (I'd never tip a counter employee).
I have thought about not tipping a few times for shitty service but I don't have the stones to do it.

This is in the US. In CR, a 10% tip is included. I only tip above that for exceptional service. Standard service gets the standard tip.