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.
Mawers of the experienced trainer apparently did not give rest to the sexy lady, made fun of herself to start with, and then arranged a merry-go-round fuck showing how to do it and how deep it is necessary.