Cleave gag
From wipipedia.org
A cleave gag is a more effective variant of the OTM gag. Instead of being tied over the bottom's mouth, the scarf or cloth is pulled between his or her teeth. While a thin material isn't very effective, a thick scarf can be used to hold his or her mouth open, and the tighter that gag is tied the better it works. Occasionally, a knot is tied in the centre of the gag so it works more like a ball gag.
