Anyone who has ever sprinted at full speed completely naked and fully erect will understand—it's hard to run like that. It swings around regularly like an upside-down pendulum clock, and way more dramatically than you'd expect. Even though its weight shouldn't be any different from usual, the centrifugal force makes it feel like there's a heavy weight attached to the base of your crotch. It's a strange sensation.
And then, every so often, the glans smacks against the underside of my stomach with a pechin.
Pechin.
"Hauu…!"
I slow down slightly.
Once the sweet numbness that ran through my whole body subsides, I accelerate again.
And then—
Pechin.
If I were a woman, the glans would be hitting right where my uterus would be.
"Hauu…!"
I slow down a bit again.
This cycle repeats.
