Well... I work in food service at a college. At a line job nonetheless.
What I hate are the customers who go through the line talking to their friends, giggling and sometimes being obnoxious, then when you ask them what they want, they stare at the menu and go "Uhhhhhhhhhhhhhhh". The menu is huge and is in broad site.
Also, people who are nasty to retail workers for things beyond their control. Kind of ties into the last pet peeve, as similar situations occur in food service AND in retail. I went into GNC the other day and this guy was *****ing out the hourly Sales Associate that they didn't carry Carnivor (no E at the end of this drink) when that is the General Managers problem for not ordering it. Customers are always right, but also customers, treat people how you want to be treated.
When people assume I'm Iraqi just because I say I'm Arab.
On a related note to the last pet peeve, when my Hookah is burnt out but I'm too comfortable to make a new head.
Anybody who acts like a ***** because they are hot (News flash... There are actually nice good lookin girls, don't get bigheaded).