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
Gustave	goo-STAHV	French
Leandros	-	Greek Mythology
Haroon	-	Urdu
Pompeo	pom-PE-o	Italian
Bjarne	BYAHR-ne (Danish)	Swedish, Norwegian, Danish
Lise	LEE-se (Swedish, Norwegian, Danish), LEES (English), LEEZ (English)	French, Swedish, Norwegian, Danish, English