Inhibitor spike

Also known by the euphemism mouth flowers, inhibitor spikes are horrible Decepticon restraining devices. They are screwed directly to the roof of the mouth, sending a telescopic metal spike through the subject's brain if they attempt to remove it or transform.

Fiction

IDW Generation 1 continuity

Early in the war, Skids was captured by a Decepticon hygiene team and incarcerated in Grindcore. There, he was taken to the "fitting room" where Flywheels gleefully introduced him to the "mouth flower". When another prisoner enquired what the Decepticons did if a Transformer didn't have a mouth, Stalker was only too happy to demonstrate how they improvised using a large, bladed weapon. Speak, Memory: Part 1