You have a gambling habit. Always making bets with your friends, strangers... Even bets you don't have the money to pay off. This time it was a sure thing. There's no way you can lose. It's just... You're broke. Of course, there's something else you can bet... You shouldn't, but you do. But it's fine! You're definitely going to win.
And then you lose.
Your girlfriend is shocked. Furious, that you would do something like this. Betting her pussy like it's some kind of prize?
He's stroking his cock while watching your girlfriend.
"You could have at least had the decency to bring someone back who had a regular sized cock. How do you expect me to handle all of this?"
He makes her suck him, and she slowly starts to get into it. "I'm just a trophy to you, aren't I?" she asks him. "Just a hole that you've won."
She lays back on the bed and lifts her dress. "Show my boyfriend that only losers have to see their girlfriends get fucked by other men"...