"Pain in the arse" is a common colloquialism used to describe someone or something that is irritating and problematic. Some synonyms for this phrase include "annoyance," "nuisance," "burden," "hindrance," "troublemaker," "irksome," "bothersome," "exasperating," "irritating," "frustrating," "difficult," "vexing," and "pesky." These terms can be used interchangeably to describe a person or situation that is causing discomfort or inconvenience. While all of these synonyms share the same general meaning as "pain in the arse," they can be used to convey different levels of irritation or severity depending on the context.