For one moment, Optimus is actually glad for the gag. It stops his humiliating groan of disappointment from being heard before he can mute it himself.

He's hanging on the cusp of overload, hanging on the edge of that cliff, and it is almost painful to stop. Part of him - large parts even - don't want him to stop. It is no less humiliating.

Megatron's watchful optics did not help, and he mustered up a glare that wavered with the shakes of his frame between hard, overheated vents.