We present results from a “corruption game” (a dictator game modified so that recipients can take a side payment in exchange for accepting a reduction in the overall size of the pie). Dictators (silently) treated to be able to take more of the recipient's tokens, took more of them. They were also more likely to believe that recipients had accepted side payments, even if there was a prize for accuracy. The results favor the hypothesis that people avoid altruistic actions by distorting beliefs about others' altruism.