They get 'distracted.'

As they continued their make-out session in the bushes, Jane grinned at him. “So you've had a blowjob once or twice, right Bryan?” Bryan nodded, wondering what Jane had in mind for him. “I've got a quick question,” she said leaning in for another slow kiss. “Do you want tonight to be 'special'?” Jane used the finger quotes to emphasize the word.

“What do you mean by special?” he asked. Jane giggled.

“Well, and there's a couple of conditions that need to be met. If I get you off again, will I get that cock in my pussy?” Bryan looked around and shrugged. Jane laughed. “Do you think if you cum again, that I can get you ready to fuck me later. We'll have the walk back to stay horny. And I can be pretty convincing.”

“I'm sure if anyone can get me hard, it's you.” Jane looked at Bryan, weighing the options. Finally she shrugged.

“It'll be worth it anyway,” she told him. “You still hard?” she asked. Jane took another look around the bushes, then lifted her shirt over her head and folded it. “Hold this,” she told Bryan. Bryan simply nodded, his eyes honed in on the two beautiful globes just released. “Cold,” she hissed, then smiled. “Pull out your cock.” Bryan, still entranced by the two breasts just revealed to his eyes, nodded his affirmation, then acquiesced to the request. His hard cock stood out, quivering in the cool air. Jane smiled, then licked the dick in front of her, using copious amounts of spit. Without a word, Jane looked into Bryan's face and wrapped her two breasts around her new beau's cock, and slowly slid them up and down, coating the two tits in her own spit to help lubricate the channel of flesh. Bryan groaned, his head lolling back.

“This is a tit-fuck, Bry. Do you like it?” Bryan mumbled incoherently as the saucy student continued her slow stroking of his cock. “I figured you would. And it's special because not every girl you meet has the equipment to pull this off.” Bryan heard some people walking by the bushes and nearly froze. Jane smiled, and making sure she had Bryan's attention on her face, licked her lips. “Kind of exciting, isn't it?” she whispered. Her steady rhythm never faded, even through the walkers' voices passing by. “Now, let me get to work.” She increased her pace, occasionally taking Bryan's throbbing cock back into her mouth for lubrication. Bryan's senses were overwhelmed; part of his brain focused on the incredible sexual experience, and the other part was checking for any intruders.

“Fuck my tits, Bryan. Fuck these big tits.” Bryan groaned as Jane started a different kind of oral treatment. He watched his cock, now larger than it had ever been in his young life, slide between her pale tits in the dim light.