There was a faint, staticy groan from Megatron due to those infernally wriggling hips, but he refused to let himself be hurried. While it was slightly hard because of basically having to work with his hand behind him and being somewhat in the way, Megatron simply shifted his grip enough to be able to stroke the cables in the gap between pelvic armour and hip joint.

"Good. It's pleasant to see I don't need to do more explaining," Megatron said with a slow smirk, his other hand idly stroking the base of a pair of cables. His optics dimmed and then flared at the aroused encouragement he was getting over their curious link.

What came in return was want and a teasing thread of not sure I can hear you are you sure you want it? as Megatron chuckled, pressed the length of his finger up against the outside of the valve, tapping against it before pushing in.

Not the whole way, but at least more than playing around outside?