Gender difference in humor

On average men are slightly funnier than women.
According to this meta-analysis men were rated as funnier with the effect size of d=0.32, that means that if you picked any random man and any random woman, there is a 60% probability that the man is funnier then the woman.
Evolutionary-minded scientists have proposed that humor is a sexually selected trait in men that signals mate quality. Indeed, women tend to prefer men who make them laugh and men tend to prefer women who laugh at their jokes.
Social pressure is likely to play a rule to, people are aware of the stereotype and it can influence people as a self fulfilling prophecy.
Correlation of d=0.32 can also be shown using the BESD technique. Imagine a room with 100 men, and 100 women. If we ranked each of these people on how funny they are and then only looked at the top 100. We would expect to see 58 men and 42 women.