Finally

The feeling of Emma's 18 year old mouth around your cock was almost too much. You felt her lips close around your shaft and her head started slowing bobbing up and down. After spending half the day with her in nothing but a bikini and listening to her talk about sucking cock, there's no way you could last long.

"I think I should do what he did," as you reached forward and slid your hand into her bikini top. Your hand cupped her perfect little breast, feeling a hard nipple poking into your palm. "You're doing a good job, Emma. That feels so nice."

She paused and smiled up at you, "really John? Thank you!" and slipped her mouth back over your cock.

As blowjobs go, it was actually mediocre, but the buildup meant you were close to bursting already. You watched your cock slide in and out of Emma's beautiful girl-next-door face for as long as you could hold back.

"Emma, you're doing so good... you're going to make me cum soon."

She looked up at you and smiled but then with a little concern, "oh... where will you...?"

"I think I should come in your mouth. That's what your boyfriend should have done and I think you should practice."

She looked worried, but said "yeah... um... that makes sense."

Her willingness to take part in the lesson was too much, and you didn't get to enjoy her practice for much longer. "You're going to make me cum, Emma."

The bluest balls you have ever had erupted into Emma's mouth. She squealed with surprise as the first cum hit the back of her throat.

With your second pump, she pulled back "oh my god!" Your balls weren't empty yet, and more ropes of jizz hit her chin, neck, and chest. Eventually, the eruption stopped.

Emma sat back, looked away from your drained cock, and up at your face.