A crazy person; a crackpot or lunatic.
Craziness; insanity.
In a crazy manner.
Madly; extremely or obsessively.
Obsessed; overly enthusiastic.
Ridiculous; unbelievable or silly.
Crazy, insane.
Fraught or out of control.
A sociopath.
Having the characteristics of a sociopath.
Unconcerned about the adverse consequences of one's actions on others.