For me, it is the stupidity, ignorance and inconsideration exhibited by most of humanity when they come to shop at my place of work. The following are the most common:
-Customers going behind the tills.
Surely this is obvious; behind the tills is staff only EVERYWHERE.
-People who assume that if a product is near a special offer POS, the POS must therefore refer to it, regardless of what the POS actually says.
Read the damn label before you make a scene, dumb-asses.
-People who cannot ask properly for the item they want from behind the counter. There are five different varieties of AA batteries behind the counter, but the fools will disregard this fact and simply ask for AA batteries as if there is only one brand, pack size and quality level.
Simple observation, people. Look before you ask.
-People who want a particular item, but call it by another brand's name. It is as retarded as wanting to buy a PS Vita, and calling it a GameBoy, or calling Fanta Tango, etc. I don't care whether it is street slang or whatever.
You call it what it says on the packaging, or you describe it by appearance if you don't know that name.
-People who call something by a name that it ceased to be called by before I was born.
Get with the times.
-Racists coming to me for service before my colleagues are not British, and then having the nerve to talk to me as if we are like kin for being the same nationality, and complaining about the amount of foreign staff.
Race, nationality, etc, are worthless labels. They do not define you, only your actions will do that.
/end rant