Try Another Type of Stimulus

Standing on her knees between Sam's legs, Dr. Poppinpuus removed her blouse, freeing her extremely round DD breasts, then looked up at her patient and explained the procedure.

"To see whether or not there's a connection between the reaction in your knee and the reaction in your penis, I need to stimulate your penis and see if it make your knee twitch. The best way to do that, I believe, is to slide your manhood between my breasts." She gave them a little shake. "That way I can stimulate all... Well, most of your penis while being able to observe your reaction. A handjob won't cover enough surface area, and intercourse would obscure my view of your leg."

"That makes sensssss..." Sam's response drifted off the busty doctor opened her mouth slightly and allowed saliva to drip down her chest and between her tits.

"You like that," she said, smiling. Sam nodded. "Well then you're going to love this."

Dr. Poppinpuus grabbed the base of Sam's member, pointed it directly up, then wedged it in between her tits. She straightened her back and started messaging her nipples. The squeezing and kneading of her breasts slowly slid her tits up and down the sides of his cock.

After a few tugs, she turned her attention to his leg. She titfucked him in three-second intervals, systematically testing many different rhythms. She started with one stroke per second, and got faster and faster. His leg never moved. After six tests or so, she had clearly given up on the test and put her energy into her tittyfucking.

"Well..." She said, huffing as her chest heaved up and down on his fuckstick. "That was a bust." She smiled up at him. "Of course... That means... I don't... have to save... a semen sample."

The doctor released Sam's cock, then gave it a quick kiss. When his precum touched her lips, she moaned and went back down on him. She slid as much cock as she could down her throat, until the tip tickled her tonsils. She gasped when she came back up for air, but then smiled.

"I take it back. We are definitely going to need a semen sample," she said. "A few, in fact." She thrust the cock back between her tits. "Luckily you've been excused from your activities so we have plenty of time.

Right now, I want you to blow wads of hot, creamy cum all over my face and tits."

Poppinpuus started sliding her spit-slippery milkbags up and down Sam's manmeat as fast as she could.

"You like that, baby?" She egged him on. "The doctor wants you to cum. Are you gonna cum for dr. 'popping pussy?' Yeah I know that's all you guys can think about when you meet me."

Sam started thrusting in time with the doctor's strokes.

"Yeah... Think about sticking your thick, hard sausage inside my hot Bavarian creme pot," she kept going. "If you give me your tasty cum I might let you POP my pussy!"

"Unnnhhhhhh!" Sam let out a deep groan, thrust hard so that his cockhead popped out of the top of Dr. Poppinpuus' titfuck-tunnel and sprayed his cum all over her face. The second shot mostly went in her mouth. By the third, the cock had come loose and sprayed on her tits and stomach.

Surprisingly, Sam's cock did not go down after the cum stopped flowing. He looked back at the IV he was still attached to, then back at the doctor. "What is that stuff?"

"Hmmmm," Dr. Poppinpuus said, "Well that is interesting. Clearly we are going to need to perform some more tests before you go."