You´ve made a bet with your girl and she lost it.
Time has come for you to collect the prize and you tell her that what you want is to see her being fucked by another guy.
She agrees but only if she can pick the guy. You tell her it´s not a problem until she picks that annoying cousin that is always bragging that no girl can resist him.
Not only he can add one more to the count…your girl, but he can also brag that he gave her huge orgasms!