Scams when selling on Craigslist or ebay

Got a phone call one day from some guy (with a middle eastern accent) claiming he was from the US department of defense , bla bla bla, I said NOOO YOUR NOT! He says YES I AM. I said NO YOUR NOT! This goes on till he gets pissed off and hangs up on me . laughed my but off. Sad thing is , he probably was.