in someone's hair

Idioms  

1. Annoying or bothering someone. For example, She was constantly in my hair, overseeing everything I did, or Dad was working on taxes, and the children were getting in his hair. This expression alludes to entangling one's hair. [Mid-1800s] The antonym, out of someone's hair, is often used as an imperative, as in Get out of my hair! [c. 1900]

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Example Sentences

These racial classifications were often decided on the basis of photographs or superficial observations, including the infamous "pencil test" in which a pencil was put in someone's hair - if they shook their head and the pencil fell out, they were classified as white, but if it stayed in, they were not.

From BBC

A hand placed on someone’s chest, or in someone’s hair, might signal either invitation or rejection.

From Washington Post