Simple Agony
She has you kneel right at the edge of her chair, reaching down and finally showing the vibrator she has in hand. She explains a little more of what you will be going through while tying the vibrator to the underside of your hard cock, making sure it fits snugly under the shaft and tip.
(Go ahead and tie your vibrator to your cock or prepare your toy/lube as needed.)
“You see boy, this vibrator has only one button. On and off. Most of the girls love coming up with all these intricate ways to tease you. Stroke like this, sit like that, edge this way. Not me, because I know a little secret.
“Things are much more intense when there’s only on and off. I’ll even give you the button, just don’t screw it up boy. From here on, that button is the only way you get to stimulate your cock.” She giggles a little, watching your reaction.
“Oh, but before we start, use that dial there. Set it to the right intensity for you. Make sure it’s powerful enough that it will make you cum if left on, but low enough that you can control yourself. Once you choose you can’t change it and we’re starting!”
(Whatever toy you are using, choose a speed and pressure now that you can stick with for the entire tease. This speed and pressure must stay the same as much as possible so your only way to control how aroused you are is on/off or start/stop.)