Forehead blister

The latest flouncing, smirking, thrusting little irritation that's about to give me a hemorrhoid on my forehead is the tip-swivel, the pay screen at the counter, with various outlandish tips suggested--for a cup of coffee. I nearly sprained my back lunging at the No Tip option when the server turned away to get my richly deserved cookie. Can anyone help with this? This situation? Now I have a pain in my butt to go with the throbbing growth on my forehead.