get under so's skin meaning

[American slang]
Fig. to bother or irritate someone.
  John is so annoying. He really gets under my skin.
  I know he's bothersome, but don't let him get under your skin.

• get under one's skin:    Verb: get under on ...
• get under someone's skin:    1. To annoy someon ...
• get under sth:    [American slang]to ...