I once read the surgical protocol for emergency treatment of acute priapism.

There are two successive things to try: first, stabbing a very thin-bladed knife directly downward through the glans on each side of the urethral opening, and if that doesn't work, making lengthwise incisions in each side of the spongy tissue on the underside of the penis.

If you have a Swiss Army knife or similar on you, demonstrating this on a banana is a great way to liven up a flagging conversation during the fruit course.