Person 1: I'm oh so hungry, if only I had something sweet and delicious to go with this bitter coffee!
Person(?) 2: Fear not my friend! Have some of my gangrene to combat the morning hunger!
Person 1: Thank you so mu- AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHH
Gangrenous penis is where a male's penis is restricted from having blood flow for so long that it dies, causing the tissue to rot while attached to the body.
It's when you get gangreen on your penis. It's disturbing and probably means you will never get laid again. Also, don't even try to get a boner when you have it. Sadly, chopping it off is the only way to get rid of it. I do not know how you would get gangreenis, except if you were buck naked and running through antarctica.
I hope I never see that guy's gangreenis again! It ranked in the top 5 of most disturbing things I have ever seen!