Heres my top ones as of late... I work in a restaurant so that'll be the basis for some of these.
Parents. The world is not your family room. If I am sitting in a restaurant, I should not hear your childs death screams nor should I witness them running about. Yes, they are just kids... but you are not. Take them and leave.
People that complain about their service at businesses yet argue against paying enough to have better employees.
People that show up with $300 retro jordans and an $800 iphone while smelling of expensive weed and then proceed to order 3 rounds of top shelf drinks, multiple appetizers, an entree each, a dessert each then are suddenly broke when it comes time to tip.
People that ask for an empty glass and then use it to spit their chewing tobacco in. FWIW we throw those out.
The crazy amount of people that ask for one thing, then ask for one more thing when you get back... my record is 5. No joke.... 5 consecutive times.
People that completely fabricate a complaint ABOUT YOU in order to get free things. Listen, you're cheap... we get it... say the food was cold or it didnt taste right.. or say that you were bothered by some other guests. But dont straight up lie about somebody that could lose their job because you wanted free champagne.
Bands that play before you and then take FOREVER to get their gear off the stage...as if they're golden gods and the show is now over.
People that were in such a rush that they just HAD to pull out in front of you but are now suddenly in no rush at all and take a quarter mile to get up to the speed limit.
The paradox of people on this forum that are only inconvenienced by repeated topics or a lack of using the search function because they cant stop themselves from clicking the thread, typing the same generic response, and cluttering the replies. If its been discussed and you dont want to discuss it again, move along.