1. Law. the crime of willfully inflicting a bodily injury on another so as to make the victim less capable of self-defense or, under modern statutes, so as to cripple or mutilate the victim.
2. random or deliberate violence or damage.
3. a state of rowdy disorder: Antagonisms between the various factions at the meeting finally boiled over, and mayhem ensued.
4. To Really do someone or something very bad, or very good
the FEDS went Ham on Michael Vick
Don't Make me go Ham on your candy ass