There's a certain type of creep who'll go out of their way to harass or grope waitresses and waiters.
I'll never get people who think that they can invade someone's personal space without being annoying, rude, or disgusting. Like people who slink up to you and put their arms over your shoulders, or nudge up in your business to see what you're eating, or look at your computer screen when you're working when they have no idea if what you're looking at is something you'd rather people not see. No, I'm not just talking about weird NSFW videos, but yeah, those totally fall under that umbrella as well.
Even worse are those who think it's OK to just touch/grope you out of nowhere, especially in situations where it's completely uncalled for. If you're drunk in a club, and you like the way someone's grinding on you, you grind back. If you're partying and vibing with another person, and they start getting handsy and you like it, then get handsy back.
But if you're a patron at a restaurant, then I'm sorry, but the only thing you should be putting your hands on is a chicken club sandwich, not your server's butt.
And because I'm well-endowed in matters of the posterior, I've gotten my fair share of booty slaps, and each one got me angrier than the last. People always have the same dumb grin on their face after they do it, too.