A seeming incurable made up disease that affects only guys, and is extremely deadly. An excuse you can use to get out of sticky situations that makes yourself look like a total douche. Don't use it, unless you're trying to get out of marriage. Then be my guest.
"Uh... I don't think he could make the wedding. He died. He had Incurable Dude Cancer."
"I can't go to the meeting, I have Dude Cancer."