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Reactions towards and perceptions of unfair offers in the ultimatum game have been studied extensively. However, little research to date has focused on people’s understandings of hyperfair (altruistic) offers – that is, offers that are unfair in one’s own favor. Participants played a version of the ultimatum game in which they received a fair (50-50) or hyperfair (80-20) offer from a confederate proposer. The present research demonstrated that compared to fair offers, hyperfair offers led to increased positive mood and decreased negative mood, such that those initially reporting low positive mood were most positively impacted by a hyperfair offer. Secondly, people avoided interpersonal contact with those who were hyperfair and perceived them as being less conscientious and more open. Although hyperfair offers did not have any significant impact on people’s donations to charity, an interesting trend emerged: participants who donated to charity thought of their hyperfair proposer as being more extraverted, more agreeable, and less neurotic. These results have important implications for our understandings of altruists and altruistic behaviors. ii