be a thorn in (someone's) flesh/side

someone or something that keeps annoying you or causing you trouble.

A relentless campaigner, he was a thorn in the government's side for years.

• wheel and deal
• wheeler-dealer
• wheel has come full circle.
• wheel has turned full circle.
• wheeling and dealing
• wheels are turning
• when all is said and done
• when back is turned
• when hell freezes over
• When in Rome .
• When in Rome do as the Romans do.
• when it comes to the crunch
• when push comes to shove
• when ship comes in
• when someone's back is turned
• when someone sneezes, someone catches a cold
• when someone sneezes, something catches a cold
• when someone was a mere twinkle in father's eye
• when someone was a mere twinkle in their father's eye
• when someone was a twinkle in father's eye
• when someone was a twinkle in their father's eye
• when something sneezes, someone catches a cold
• when something sneezes, something catches a cold
• When the cat's away .
• When the cat's away the mice will play.