"Do you think you can hold one more edge for me slave?"
"I don't know mistress, i will try if you demand it"
"Oh..i will demand it slave.."
"Don't worry about that.."
(You give here a concerned look)
"Keep stroking.."
"Use 2 more fingers from your other hand now.."
"Y..y..yes mistress"
(The uncomfortable position makes you shake a little bit)
"Ok.."
"Stroke yourself to the very edge and hold it with your 4 fingers slave"
"Show me how serious you are about this"
"Feel your orgasm, but don't go over the edge!"
"Y..y..yes mistress"
(You try to relax your muscles and start holding the edge)