get one's hands dirty and dirty one's hands; soil one's hands
1.Fig. to get closely involved in a difficult task. You have to get your hands dirty if you expect to get the gutters cleaned out.
2.Fig. to become involved with something illegal; to do a shameful thing; to do something that is beneath one. The mayor would never get his hands dirty by giving away political favors.I will not dirty my hands by breaking the law.