That's the kind of slutty sister every brother would let work his testicles. And this one probably accustomed her to these pranks a long time ago. At least that's what I would have done. She'd have to suck and spread her legs anyway, so why not with her own man? It's about time she got her ass printed, too, so she can date like a grown-up bitch. Or maybe she's still trying to keep her anal virginity for her husband.
If your girlfriend is a bitch, then consider that variety is guaranteed for you. Look - this cutie doesn't mind getting laid by a stranger for money if her boyfriend allows it. What I find most endearing about this situation is that she doesn't cheat on him, but lets him decide the matter himself. That turns her on more than the sex. When he took the money and counted it, I got a hard-on. Deciding who can fuck your girlfriend and who can't is adrenaline and high. Don't tell me he fell for the 20 scoops of ice cream she promised him for that money. There's more to it than that. )
She looks like a milf...