Then, just as you are about to pop, she says:
"OK! Let's see if you can hold back when your cock is in my mouth!"
She proceeds to grab your cock with both hands, and then slowly and tantalizingly she licks the tip of your cock in ways that make you definitely want to let fly all your sperm. You can't control yourself and your cock stretches out and twitches under her teasing tongue.
"Oh, yes," she says into your cock, as if it was a microphone, "I can feel you twitching!"