I hate it when people don't know what they want when they're at the register and especially if theres a line, and they hold up the line. And also (idk if I mentioned it before) when they stand AWAY from the register, (and no one is at the reg) so I go and ask them if they have a question and they start ordering.
And when people try to give you money when you're not at a register.
When you call out an order like 5 times and the person isn't paying attention
All of this. It's like they've never ordered before.