When a penis has been in contact with water for an extended period of time, whether it be bathing, swimming etc. The penis then becomes shriveled and wrinkled to the point where it is a fraction of normal size.
"Jody totally wants my d"
"What are you waiting for? Make a move!"
"I don't know I'm not really attracted to her I doubt I could even get hard."
"Don't let that stop you, just shrivel dick her!"
An insult used by internet trolls and tryhards who use death threats. Basically the troll/troll wannabe hates the person hates so much they want them to shrivel up and die in a horrible manner.