He works in fast food. I know spongenob is dumb but there's no way he's unhygienic enough to wring it out and get wee all over his spongey hands.

Nay I think for it to function as a penis is intended, it must only have one hole

And after all, we know some humans have spongier penii than others. Which basically just means your erect wee wee is less hard and boney-feeling than others at its maximum blood capacity. So we must assume that is what happens here