You *can't* wait any longer

You're too close to stop now; in fact, you're so close that just the feeling of her pussy wrapped around your cock is about to push you over the edge, even without any movement. But you can't cum inside her so you do the only thing you can from this position. You extract your dick from her warm, wet pussy and push yourself across the finish line with your hand.

"What-" is all she's able to get out before you erupt. You spew cum all over her back and ass. One errant spurt even lands all the way up in her hair. The last few bits of cum drip down between her ass cheeks.

You're both quiet for a moment as you cum down from your climax. Then she says, "In hindsight, maybe I should have told you that you can't come in me sooner. We'll be better prepared next time. Now go get me a towel."