We’ve reblogged this illustration from Boyfriend and ExBoyfriend BDSM Gallery. He’s got great taste in NSFW pics too.
This is a regular series of illustrated guides. You can find the others here.
gag: Any device or object designed to be placed in the mouth, most commonly to prevent a person from speaking or making loud sounds, sometimes to hold the mouth open. A few examples are ball gag, bit gag, inflatable gag, muzzler, penis gag and O-ring gag.