It is estimated that a trillion dollars are annually exchanged in bribes, distorting justice and economic efficiency. In a novel experiment, we investigate the drivers of bribery. Two participants compete for a prize; a referee picks the winner. Participants can bribe the referee. When the referee can keep only the winner's bribe, bribes distort her judgment. When the referee keeps the bribes regardless of the winner, bribes no longer influence her judgment. An extra-laboratory experiment in an Indian market confirms these results. Hence, our participants are influenced by bribes out of greed, and not because of a desire to reciprocate.