Doppeldildo (слэш)

“I’m calling it the doppeldildo,” Harry says casually. “A tap of the wand to turn it on, touch it to the clit or cock you want it to replicate, and…” he suits the actions to the words and then slides the tip of the toy into his own mouth. Severus visibly shudders and his prick twitches as if hit with a curse. “Every sensation copied,” Harry says needlessly. “Have you ever wondered what it would feel like to suck your own knob, Professor? Want to try?”
(A PWP in which a post-war Harry invents delightfully depraved sex toys, tests them on Severus, and Severus loves every minute of it.)