I don't think this will be the best way
to strengthen your penis. But what is your actual reason why you
need to strengthen your penis? Do you lift your sex partner using
yours? I can't imagine how this topic will occur into any
situation.
Maybe you are referring in prolonging the life of your erection
if I am correct. If you want to perform sex for more than an hour
or as many as possible, I cannot recommend taking viagra, taking
drug has a side effect on each of us who used to it.
Better to understand first the limitation of yours before you
experiment new things.