be a thorn in (someone's) side

To be a constant or persistent cause of annoyance, frustration, or trouble. My professor was an environmental activist when he was younger, and, apparently, he was quite a thorn in the oil companies' sides at the time.

Common Names:

Name	Pronounced	Usage
Adrianna	ayd-ree-AN-ə (English), ahd-RYAHN-nah (Polish)	English, Polish
Haynes	[heinz]
Dejen	-	Eastern African, Amharic
Iago	ee-A-gaw (Welsh, Galician), ee-AH-go (English)	Welsh, Galician, Portuguese
MaËL	-	French, Breton
Leopoldo	le-o-POL-do (Spanish)	Italian, Spanish, Portuguese