Mess Up Meaning

(transitive, slang) To discombobulate, utterly confuse, or confound psychologically; to throw into a state of mental disarray.

Example:   The afternoon breeze messed up my hair.
  The change messed something up, and it's not working anymore.
  Well, I messed up my solo, but otherwise it was a good concert.
  He has a hard time getting started because he's afraid he'll mess up.
  She messed up on her final exam.
  Stop bumping me! You keep messing me up!
  He messed up his elbow at the track meet.
  Her brother's friends messed him up a little after he cheated on her.
  That girl totally messed me up, man. I'm not sure who I am anymore.