He'd been close to overload as it was, and it didn't take much for Optimus' overload to become his, especially as they were still connected on more than one level, in fourteen different points (including spike and valve).

Hands tightening, Megatron lifted Optimus up a little bit once more, then dropped him down and bucked up as charge unleashed. Thirteen points were liquid pleasure, the fourteenth a more mundane crackling current and tingling charge as their overloads connected and looped together.

Megatron was aware just for long enough to catch Optimus as he fell, and while he could have stayed online, he let their connected systems drag him into safe-mode offlining and then recharge.

He'd wake up easily enough if needed.