Liplocker gag
From wipipedia.org
A liplocker gag is a device to keep two captives with their lips locked together.
It consists of a large ball gag with two sets of straps. The ball is half in the mouth of each captive; this requires the captives to have their heads at right angles. When the straps are tightened, the two mouths are pressed together in a forced open-mouth kiss.
