pain in the bum

(North America, informal) A nuisance; a source of trouble or annoyance.

(UK, Irish, Commonwealth, sometimes considered, _, vulgar) Someone or something that is annoying or frustrating.

A blunt British slang term for anal sex. The word 'bum' (British English for buttocks) does the heavy lifting here, making this one of those transparently descriptive compounds that leaves nothing to the imagination. It's used casually in British vernacular — sometimes crudely, sometimes humorously — and appears across comedy, casual conversation, and tabloid journalism. It can be used without specific reference to the genders or orientations of those involved.

Bumhole does double duty in British slang: literally it refers to the anus, but more entertainingly it gets hurled as an insult at someone who's being annoying, stupid, or just generally a pain. It's on the milder end of the UK insult spectrum — kids use it, parents occasionally mutter it, and it shows up in enough British sitcoms that it barely raises an eyebrow. The derogatory use is more about expressing exasperation than genuine malice.

(idiomatic, slang, vulgar, North America) Something or someone that causes discomfort, frustration or annoyance.