pain in the ayn
A pain in the ayn is when your butt feels like it’s been dipped in lava and hit with a hammer. It's not just annoying, it's hell on your backside.
My dad’s bad jokes are a pain in the ayn.
This long car ride is a pain in the ayn. I'm about to go crazy.
My dentist is a pain in the ayn. He won’t stop drilling.