Her arse, naturally

You hand the weeping youngster back her smartphone and tell her to get off the table and bend over it. Seconds later, she's in position, back arched, gazing at the screen upon which her paramour's visage appears. Her feet are about shoulder width apart and raised on tiptoes, but when you come up behind her, she moves them a little further to give you room to get in between. You lean forwards and address the youth on the other end of the video call.

"Bethany tells me you like to admonish her after a spanking. Feel free to do that while she tips me with an arse fuck."

The blonde turns the volume up so that you can hear his reply, but you're not waiting, instead dropping your pants to let your erection spring free and lining it up with her tortured bum hole. You hope she's well lubricated and use your thumbs to stretch her painfully open to make your entry easier, or at the very least, possible. Meanwhile, her boyfriend's words wash over you, only half heard. You hope she's paying better attention.

"Thanks, Prof. You hear that, Beth? You're getting your arse fucked by your prof. right in front of me, because you haven't called me often enough. How does that make you feel, huh? Tipping an old bloke for thrashing you for something you could easily have avoided. I hope you're crying because you're ashamed of the way you've been taking me for granted, not because you're feeling sorry for yourself. Taking the professor's cock up your arse when it's smarting from a thrashing is exactly what you deserve, isn't it, Beth?"

He keeps going, repeating himself at times and barely giving his girlfriend a chance to respond to his occasional (and mostly rhetorical) questions. You don't find it too distracting, almost like mood music while you squeeze yourself past her overly tight anal ring into her welcoming (and thankfully lubricated) rectum. What does distract you a little is the parallel pattern of old, faded welts on her back, neatly packed side by side. They're severe and skilfully applied, reminding you of your own handiwork, although you get a feeling, possibly from the Rulebook, that they belong to someone else.

Whilst Jason drones on, you reach for your student's golden tresses and use them as handles to give you leverage for deeper, harder thrusts. The girl is grunting and whimpering pitifully, although whether due to the pounding you're giving her or the verbal lashing coming from her lover, you can't tell. Your excitement enhanced by the sheer depravity of claiming your pleasure watched by your tipper's feller, you could cum at any moment, but you feel the irrational urge to impress him by your stamina. This is easier said than done, with your grad student's skilful arse massaging you constantly, thrusting back to meet you and expertly matching your rhythm, but you manage to hold out until he starts to trail off, running out of ways to castigate his sobbing young mate.

With one final effort, you spend yourself in her rear, allowing her to milk the final drops of ecstasy from you before you pull out and slap her rump in satisfaction. You need to sit down, but don't want to reveal to the young stud how much fucking his girlfriend has taken out of you, so you wait until she's tearfully thanked you, apologized to him and said her goodbyes, then sink into your seat to wait for Bethany to suck you clean.

You close your eyes to enjoy her tender ministrations, then push her away and tell her she can get dressed. You both make yourselves presentable whilst she thanks you again for chastening her and then you both leave, locking the door behind you. Teaching duties discharged for the day, you have the rest of the afternoon to amuse yourself, although you hardly imagine it will be any more satisfying that the last half hour.