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.
The cowboys know about chicks. And this one they chose for mating for a reason - she has excellent forms. After mating and working all her juicy holes - the men gave her a milk injection through her mouth. What fun uncles!