People piss me off when they don't tip. 

I get that it's not your job to pay my wage, but you know that I only make like three bucks an hour. 

If I did a shit job, that's cool. I know I did a shit job, and you know it too. But if I gave you the best service - the same service as I gave all my other tables that tipped - and you didnt bother to leave anything.... I'm gonna be pissed.