Gender changing adventure

100% MANHOOD 90% HEALTHY (little stunned)

The panties forceful hold their grip squeezing your testicles: the pain makes you unable to move.

Suddenly after you feel the tendril that, with a decided push, enters into your meatus like a worm enters in a hole in the ground: you feel the pain coming from your little stretched meatus.
After few moments it is inside you and, having reached the neck of your penis, it moves inside your pole towards the testicles, causing a little itch sensation in your penile urethra.

You look at your groin... you see your penis that, wrapped by the panties with the little viscous tendril twined around it, is now fully erected.

After that the panties, with a decided contraption, squeeze your testicles once more: the pain moves all alongside your spine reaching your brain.

Few moments later, while the testicle-ache is disappearing, you notice that don't sense the top of the tendril anymore: it's lost inside your body, now it should have reached your scrotum. In fact you feel only the slowing sliding of the tendril through your meatus.

5 second later the tendril stops its moving as if it have reached its destination.
In that moment you sense a weird sensation into your ballsack, as if something is winding around one of your testicles.
“What's happen..." the tendril stings your right testicle "...aaAAAHH” You yell in pain.
The pain is very intense, but it in few moments is disappeared, leaving you a little stunned.

What do you do?