a pain in the arse
a pain in the ass
If you think that someone or something is very annoying, you can say that they are a pain in the arse or a pain in the ass. Other words meaning `bottom' can be used instead of `arse' or `ass'. The form with `arse' is used in British English and the form with `ass' is used in American English. These are very informal expressions, which many people consider offensive.
He'd dealt with the Hendersons of the world before. They always meant money, but they were an almighty pain in the arse to deal with just the same.
Leone could soon be following her uncle and into film roles. `Having the name Connery is a terrific advantage and a pain in the backside at the same time,' she said.
a pain in the neck
If you think that someone or something is very annoying, you can say that they are a pain in the neck.
He was a pain in the neck. I was glad when he left my department.
`Sorry,' he said. `They've forgotten to insure the plane. It's a pain in the neck, but what can I do?'