on so's case meaning

• [American slang]
  Inf. harassing someone about a personal problem; annoying someone. (Typically: be ~; get ~; keep ~.)
    I'll get on Tom's case about being late so much.
    I'm sorry, I won't get on your case anymore.

• case so or sth out:    [American slang]Sl ...
• get off so's case!:    [American slang]Fi ...
• in the case of so or sth:    [American slang]in ...