It's insanely hot, and so many options. O ring or dental for ...access. Ball gag for a sexy display. Cleave gag (cloth or handkerchief) or duct tape for aesthetics and that kidnapped vibe. Panel gag or reverse dildo gag for the bdsm effect. Doggy toy for kink and humiliation. There are even ones that inflate to absolutely fill a man's whole mouth. And absolutely all of them for the various musical sound of a muffled man moaning, groaning, gagging, or yelling into them...it's my favorite. I could write an essay...