“Ummmmm…” she murmured. “I just love how the head of your cock feels against my tongue! It’s so soft, but firm and rubbery, at the same time. And it feels so smooth…”
“Yeah, it kind of feels different from anything else, doesn’t it?”
Amy gently pushed her closed lips down over his glans until her lips slipped over its flared edge and closed around his shaft. She gently sucked on his engorged glans for a moment while caressing it inside her mouth with her tongue. Then she let his cock-head pop out of her mouth and resumed slowly swirling her tongue all around that swollen knob. She very slowly traced the tip of her tongue all around the underside of its flared edge, then looked up at him.
“I wonder why it’s shaped like this…” Amy murmured musingly, then resumed running the tip of her tongue all around the flared edge.
“Actually,” Ron said, “They come in all different shapes. Mine is kind of saddle-shaped, covering the top and sides of the end of my cock. Others are more bell-shaped and wrap all the way around.”
“I read a theory about why it has a flared edge around it,” Ron said, assuming a slightly professorial tone. “Back in prehistoric times, early humans weren’t monogamous like most societies are now. The male’s cock-head evolved to have a flared edge so that, while his penis would easily slide into the female’s vagina, it would kind of press against the walls of her vagina when being pulled back out, and act kind of like the rubber plunger in a syringe, sucking back any deposits around her cervix left by a previous encounter with another guy, before this new guy left his own deposit, thus giving his own sperm a better chance to hit the genetic lottery.”
Amy let Ron’s cock-head slip from her mouth with a little popping sound. “Ahhh, yes…” she purred staring at the boy’s quivering organ and nodding. “I see…”
She gently stroked her fingertips up and down the sides of his rigid shaft, as she imagined that big, purple knob deep inside her vagina, cum spewing from the tiny slit at its tip, bathing her cervix with its thick, white gruel.
“And what’s this line here?” she asked, tracing her fingertip around his shaft just a half-inch below the flared edge of his glans.
“Oh, I think that’s the scar left from when my foreskin was removed,” Ron explained.
“Foreskin?”
Ron smiled, delighted that he could impart some of the considerable knowledge he had gained in his extensive studies of all matters sexual.
“The penis also evolved to have skin covering the head most the time. I guess its purpose was to protect the head while their dicks were hanging out there in the open all the time when people were still running around in the jungle, naked.
“After people started wearing clothes and protection wasn’t as big a concern, some societies, for various reasons, mostly religious, I think, started cutting it off, usually at puberty as a sign of manhood. Nowadays it’s usually done when you’re still a baby.”
“Oh, yeah…I’ve think I’ve heard about that,” Amy said glancing up at her brother. “Uhh…cir–…uhhh…circ–…”
“Circumcision,” Ron prompted.
“Yeah, I heard most baby boys had their penises cut, but I never could figure out what was really going on,” Amy said.
Amy gazed at her brother’s penis, trying to imagine what a foreskin covering her brother’s cock-head would look like as she continued to gently stroke his shaft with her fingertips.
“Here, I’ll show you,” Ron said. “Wrap your hand around my cock, close to the bottom.”
Amy did as instructed.
“Now stroke it up and down.”
Amy gently slid her tiny fist up and her brother’s long, thick shaft, just lightly grazing along the taut-stretched skin like Ron had originally taught her.
“Ohhhhhh, yeah…” the boy groaned, “that feels so good…”
He allowed his sister to gently stroke his throbbing hard-on for a few moments, then he gasped. “Whew! Okay…now…squeeze my dick a little more tightly as you stroke it.”
Amy did so.
“See how the skin covering my dick isn’t really attached to the meat inside, like it is on your arm or finger or pretty much everywhere else?” he asked.
“Uh-huh…” Amy murmured, feeling the warm, solid core of her brother’s penis moving back and forth through her encircling fist while the soft, thin skin, which covered it, was held motionless, by friction, against her palm and fingers and moving up and down along with her hand.
“Now, squeeze it tighter and slide your fist upward as far as you can, and watch what happens.”
Amy squeezed her brother’s stiff, hard shaft and slid her hand upward. She watched as the skin covering his cock bunched up ahead of it. The roll of skin spilled over the flared ridge of his engorged glans, partly covering it.
“If it hadn’t been cut off, that skin would go all the way over and past the tip of my cock, covering up the head all the time, except when you pull it back down.”
Amy released the pressure of her fist and the bunched up skin, instantly retracted back down his shaft, leaving his engorged glans fully exposed once again.
“If a guy hasn’t been circumcised, and depending upon the guy, some have a foreskin that will automatically pull back when he gets a hard-on, exposing the head, while other guys have to pull it back by hand. And when they fuck, it slides back and forth over the guy’s cock-head as the guy’s cock slides in and out of the woman’s vagina.
“I’ve occasionally seen guys in the showers at gym class at school who weren’t circumcised and I used to think they were deformed or something. I didn’t know until I started studying about such things that they were actually the ‘natural’ ones while I, and most of the other guys, were the ones who were ‘deformed’ by being cut.