You tip, even though you don’t want to.
The same reason why, when someone steps on your toe with a really high and pointy heel, and really hurts you badly, but when they ask ‘are you okay’ you force a smile and say ‘yeah sure’ instead of what you really want to say: “NO!! you just killed me, get those ridiculous things off your feet, or mind your step and how much do you weigh anyway…”