I once got a free pizza by using the following ruse.
i phoned up and asked to speak to the manager. i then claimed i had psychic powers and for a free pizza would give the guy an ironclad demonstration. He said if you could prove that on a telephone it would be worth a free pizza.
So i told him that his cook had long blonde hair.
He was amazed. Then thinking it was a con asked me how i really knew.
"because i just found half her hair in the pizza you guys just delivered"
needless to say i got a free pizza with everything on it (except hair this time)
but you know i just couldn't eat it.