Slang: In one´s hair

Definition: Constantly annoying; bothering someone again and again.


Example:

1) My little brother is always getting in my hair! 


2) Be careful how you fill out your tax forms -- you don't want the government in your hair.


Etymology: It can be difficult to remove something that is caught in your hair. For example, if you get chewing gum in your hair it can take hours to get it out -- and it's very annoying to do. So if a person is 'in your hair', they are annoying and hard to get rid of.


fonte: www.peakenglish.com