You made a bet with your childhood best friend - whoever's bigger gets to fuck the loser. There was no question who the loser was. Now, she gets to stuff you full of her massive, throbbing girlmeat, and all you can do is hang on while she fucks you totall
At parties your boss always boasted that he could make any woman spread her legs for him. In a drunken state you bet, for a substantial raise, that it wouldn't work on your girlfriend. It took him one hour, and she didn't let him pull out.