My dad once pulled the “there goes 5% of her tip” when a waitress at a slammed-lunch-rush-on-a-Sunday restaurant forgot his precious iced tea. I excused myself and went to the ATM at the gas station next door to get $40 cash. When the bill came, he paid for us, and as she came to pick up the receipt I stopped her and handed the money over. Dad asked me why I did that and I told him it was a lesson for him. Manners… who fucking raised these boomers?