Let me try

You sigh not liking where this is going but say "Your hands don't work, let me try". Sam looks frustrated but is so **** she just nods. As she slides closer to you it suddenly feels very real all of a sudden. Your girlfriend having a massive cock is one thing, having to jack it off is another. With a gulp, you start to reach for it before you lose your nerve. As your hand touches it you are shocked at how natural it feels to grasp it. You start to slowly pump up and down with your hand uncomfortably but Sam is getting into it, she is breathing faster down and her dick is leaking precum lubricating your hand. Memories of doing this to your old cock start to come back and you start moving your hand faster and faster jacking her off. Finally, her cock explodes under your hand in a massive spasm of cum. Most of it hits Sam's naked body but she doesn't seem to care her eyes glassy and a smile on her lips. You wipe your hand off feeling conflicted, it felt natural and making Sam happy was nice but you just weren't sure how to feel. You look down again at her and do a double take her flaccid cock is already almost hard again.

Sam says quietly "that felt amazing baby, but I told you hands just aren't working"