We test the effect of players' moods on reciprocal behavior in a gift-exchange game. To induce a "bad" or a "good" mood , subjects were exposed to a sad movie or a funny movie before playing the game. We find that a bad mood implies more reciprocity while a good mood implies more generosity (i.e. unconditional cooperation). Since high levels of cooperation are relatively more common, player 1 make more money when second movers are in a bad mood.