Man was about to get married and his best man has to cancel at the last minute. So the man asks his soon to be brother-in-law to be best man. The Brother-in-law at first is unwilling but then agrees. What soon to be husband may or may not know is her family has a tradition. Once the women in the family get married they have to give a blow job to the best man. And the thing he definitely doesn't know is her mother made a change to that tradition. She made her daughter promise to not just give a blow job to the best man but to also have sex with him.