Got asked to tip while buying a shirt at a concert. The three percentage options were 5, 10, and 15, so not nearly as crazy as this image, but still, it's kind of ridiculous. I try to rationalize tipping based on if it's a service that I can't perform. I can line up a shirt number with the box it's in and find a size, however I'm not a barber, a barista, or a chef. The percentage I give is based on setting. Standing, 10% or a buck, whichever is greater. Sitting, 20%. Barbers get 30%+.