S1 E5: Card Sharks

Ralph wants to visit a psychic but doesn't know any good ones, so he visits a Psychic Referral Counselor. To offer proof, that the psychic is real, the counselor pulls out a deck of cards and asks Ralph to pick one at random. After Ralph picks a card, the counselor calls the psychic who then guesses the card correctly. The psychic and the counselor are both frauds so how did they pull off this trick?