Ohhh, standing in line with a "nice" old lady, who insists on having the teller correct an error in the price of two products she purchased, with 8 people standing behind her at 5pm on their way home from work.
This even though there is a completely empty counter just 10 feet away where they can actually help her correct the error, instead of her taking up everybody's time only to learn that the teller is not allowed to leave her station to go check if the prices is correct.
Then as I politely (VERY POLITELY, as I'm getting angry with her), remind her to take her problem over to the other counter, she looks at me with a look somewhere in between angry, shocked and annoyed, and says: "this does not concern you, just let me do this..."
I then repeat my request, and let her know that what she is doing is quite rude to the rest of the line.
She looks at me, completely unable to see anything but herself, the teller and me being a huge pain in her side, looks at the teller again, and completely ignores me.
I had to literally bite my tungue and slowly count to 20 to not lift her over to the other counter. By the time I got to 18, she finally got though her head, that the teller could not help her, and she moved to the other counter. Not a single time did she consider that there were anyone else in the store but her. THAT can make my blood boil.