A little experiment
Awesome... Yeah I guess that's enough water... we can get more later.
Hey I see your cock is getting hard there. That's ok.. you can touch it if you want... it might make this next part of our exercise more enjoyable for you. Just don't cum... Not yet.
Ok tell you what grip your cock really hard, like your going to break it off... give me 10 strokes...
That's better getting really hard there I see.
Tie that bottle to the string around your balls... Yes, to that string. My experiment you see is about gravity.
now put that bottle down between your legs... can it touch the ground? yes? Well that's no good. Tie it up higher. So its just off the ground...
That's better... now put the bottle on some surface level with your waist.
and....