Anyone who's ever worked in the food service industry as a waitress, waiter, or delivery person knows how frustrating it is to deal with customers who don't tip. But usually, you'll have some generous tippers who even out the others, so it's all good in the end.
But sometimes it doesn't, which makes the non-tippers especially annoying. And as much as you want to call them out on their frugality, you can't.
Or you can be like this guy and share a creepy four-page handwritten note shaming the individual for not tipping you.