I tip 20% unless their shit is all retarded, because I view it as the price of playing nice. It's compulsive. I like the average server and appreciate their attention more than I hate my job. I don't eat out much, to be fair, but it's often a situation where I'm paying for the dinner only, with someone else happily fielding a decent tip, or the reverse, when I am putting up the tip after someone else has paid for a meal. That sort of back and forth is good for brotherly social muju. You can be disproportionately rewarded forever by some blokes in a dive bar for what amounts to chump money. What do you do with small money anyway? Need to fix you car? Sort it out and then literally just spend that level of cash on your interactions with people. Inject it. 90% of it is food. Humans are obsessed with food. Hack the brains of everyone you know with this one simple trick. Tipping is basically a systemic abuse of the wisdom of generosity, so pick a rate you can feel good about in front of people and don't let it get out of hand, but I say: don't let such an amount of money affect your life undesirably when you choose to participate in social events.