People who force you to be irritating.
True Story:
I used to frequent a pet shop that sold bags of live daphnea (water fleas). I bought them for my fish. Each time I bought some, the shop assistant would first ask me, "How many would you like?" and I'd reply, "Ooh, I dunno, about a hundred?"
The very first time I replied with this, she groaned and laughed slightly. The second was a little more awkward, but I couldn't stop myself and, after years of this, she would just frown at me as if to say, "You're not funny." Then I'd look at her as if to say, "You hate me, don't you." Then she'd look at me as if to say, "DIE!" before handing me a bag of fleas. I'd give her the money, we would share forced thankyous and I'd leave.
The thing is...she never ONCE said, "How many BAGS would you like?" EVER! So, I'm sorry, but she brought it on herself.
She eventually stopped working there, which was a relief, because I was still buying water fleas after my fish had died and really needed an excuse to stop doing that.