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
Kipling	KIP-ling	English (Rare)
Xochitl	-	Native American, Nahuatl, Spanish (Latin American)
Moses	MOZ-əs (English)	English, Jewish, Biblical, Biblical Latin
Mensur	-	Bosnian
Posie	PO-zee	English
Aemiliana	-	Ancient Roman