Why does semen become rubbery underwater?

And, yes. But then again, please use a less horrible expression for your autoerotic activities. read more

Semen is designed to harden in water, but when combined with the enzymes in saliva, it is much more effective. Early proto-humans would use a liberal mixture of semen and saliva, presumably working in groups, to coat pregnant women in a sort of tough, flexible shell that would help hide their scent and protect them from predators in the very vulnerable weeks leading up to childbirth. read more

Your semen can also change in consistency and appearance in the minutes after leaving the penis and in so many males, after the ejaculation, proteins contained in semen can cause it to become thick. That is the answer to your question. read more