To be a pain in the neck

If someone is very annoying and always disturbing you, he/she is a pain in the neck. 
Syn: nuisance, pest, a drag

• Filling out the forms for my recent insurance claim was a real pain in the neck.- casse-pieds
• This assignment is a pain in the neck. Your little brother is a pain in the neck.

Slang: 
it's a drag! - ca me rase
what a drag! - bonjour la galère