:: Ask him to fuck you.
[[You]] pull your head off [[Billy]]'s dick, causing him to groan in frustration.  You look up at him and smile as seductively as you can manage.  "Would you like to, you know..." you say.

"What?" he says, a little snappishly, apparently annoyed that you stopped right when he was about to come.

"You know, fuck me?" you ask.

"But you don't...oh," he says.  "You mean you want me to fuck you up the ass like my stepfather did?"

You blush.  "Well...yeah.  You know, if you want to," you respond.

"Feeling guilty for fucking my stepfather and want to make it up to me?  Or are you just a slut?" he asks.

[[I want to make it up to you.]]
[[I guess I'm just a slut.]]