I don't send back food (unless what I've received is just straight-up not what I ordered), I'm always polite to waitstaff, and it takes a lot for me not to leave a 20% tip. (I think I've tipped less than 20% maybe twice in my whole life.)
For example, maybe the way I stack dishes at the end of a meal actually isn't all that helpful? (I've heard a lot of takes on this one.)
Or, maybe you've had absolutely awful people who were rude to you about something you have zero control of, like something being taken off the menu.
Whatever it is, if you've ever worked in a restaurant, head to the comments and share the things customers do that always get on your nerves for a chance to be featured in a BuzzFeed Community post.