We address the role of the incidental emotion of disgust in the Ultimatum Game. Participants had to choose whether or not to accept a €2 offer from a €10 pot made by another participant; 120 were in a room where a disgusting smell was released and 120 were in a room with no particular smell. Acceptance rates were higher in the room with the disgusting smell. The effect was mainly carried by the male participants who also reported more disgust with the disgusting smell and judged the offer as less unfair than females. We propose a spontaneous discounting explanation. Acceptance rates were higher in the room with the disgusting smell because participants misattributed the disgust induced by the offer to the ambient disgusting smell.