Laura Beck is right — if you’re budgeting to go out to eat, you need to include a tip in that. And you need to tip even if your waitress isn’t as pleasant as you’d like, and even if the service is imperfect. It is a gender issue, and servers (who are disproportionately female) need tips to make a living wage. I also suspect that female servers are more often on the receiving end of a bad tip for not adequately stroking a diner’s ego — not laughing enough at his jokes, not flirting back, not smiling. So tip! Yes, 20%, even if the service was mediocre.