The surprising benefit of passive-aggressive behaviour at Christmas parties: being crowned king of the crackers.

OBJECTIVE To test the effects of technique and attitude in pulling Christmas crackers. DESIGN, SETTING AND PARTICIPANTS A binomial trial conducted at a Christmas-in-July dinner party involving five anonymous dinner guests, including two of the authors. MAIN OUTCOME MEASURE Number of wins achieved by different strategies, with a win defined as securing the larger portion of the cracker. RESULTS The previously "guaranteed" strategy for victory, employing a downwards angle towards the puller, failed to differentiate itself from random chance (win rate, 6/15; probability of winning, 0.40; 95% CI, 0.15-0.65). A novel passive-aggressive strategy, in which one individual just holds on without pulling, provided a significant advantage (win rate, 11/12; probability of winning, 0.92; 95% CI, 0.76-1.00). CONCLUSION The passive-aggressive strategy of failing to pull has a high rate of success at winning Christmas crackers; however, excessive adoption of this approach will result in a complete failure, with no winners at all.