The Cloth-Gagged Witness
A cloth gag is usually close to useless, but well-packed and tight it can at least be visually appealing:
This one is from the cover of OSS.117 #57.
Elsewhere on Bondage Blog:
Bondage Blog
Taking Pleasure In The Beauty Of Restrained Women
Well, so then tickle her–so that she laughs and opens her mouth–while simultaneously tightening the gag. Ta-dah! You’ve now created a cleave gag. Well done!
(Still more effective in fantasy than in real life, but anyway.)