Cerberus

Cerberus, the hound of the underworld, stood guard at the gates of Hades and prevented those not permitted from entering. He is usually described as a beast with three heads and the tail of a dragon. When Aeneas journied to the lower regions under the guidance of the Sibyl, he brought along a medicated cake to drug the animal and insure their safe passage. To throw a sop to Cerberus means to give a bribe and thereby ward off an unpleasant situation.