How do you act like a Psychopath? I dont want to be one, just pretend.?

Wear some creepy clown costumes and carry weapons, fake ones if this is a prank. And also be as quiet as possible.

Don't show any compassion for anyone - none. It's something that all psychopathic people aren't able to do.

Well psychopaths mostly act like normal people, in order to charm and manipulate people into doing their bidding, and to lower potential victims' guard by getting emotionally close to them. So... just be yourself I guess, but with more pizazz and magnetism.