Servers, what is a minor thing that infuriates you about the guests eating at your restaurant?

Servers here complaining about annoying customers, I think you know as much as us that some people have a different side to them when they enter a restaurant. I've gone to eat with several pleasant people I know in 'real life' turn into restaurant patrons from hell, holy crap this one dude was giving me all kinds of suggestions on my house purchase one day which I had no idea about (he works in real estate and he makes bank and he basically gives his friends suggestions and info for free), anyway, we go and eat at restaurant and he's complaining to the server about this and that, i felt sorry for the servers there but I did understand why he was so rich, the dude doesn't fuck around.

/r/AskReddit Thread