I don't know...

"Hmm, I'm not sure, I think it might take a little more" you say.

"Like what, please sir. I can not stand another minute of my sister being a dumb imbecile." she pouts

"hmm, I think you might have to fuck me"

"No I-"

But you cut her off

"Oh I'm sorry, do you not remember my name?"

You her to the bathroom where you slowly strip her clothes off, your cock is already hard from when we was getting a blowjob a few minutes ago.

She leans up against the wall and spreads her big ass to reveal a tight pussy. You slowly put your cock in back and forth and back and forth, until you cum in her tight ass.

"I give your sister permission to cum now"