Start pumping

After a few seconds of shock, the weight of his expectations hit you. As far as you see it, there's a much worse option waiting for you if you don't follow his implicit command, and so your hand slowly slides up his shaft; a hefty, bumpy creature with small fleshy spikes that you shudder to imagine inside you. The thick precum it continues to produce itself slides down to meet your hand, making a squelching sound as you pump up and down. Bowser's breathing gets heavier, and you start to speed up as you gain the confidence to try and end this quickly. He tightens his grip and grunts in response to the change of pace, and just as you feel him getting close, he grabs your head and pushes it near the tip.

"Kiss it."

With his claws gripping you tight, you don't even think. You plant a kiss, and immediately a geyser of cum erupts from his member, seeming to hang in the air for a moment before drenching you, or more accurately, the hand that was gripping the top of your head. Bowser laughs, wiping the hand off on your dress, and leans back with a contented sigh.