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A slang term for having an erection, or 'hard on'.
Derived from the similarity between 'hadron' from paricle physics, and 'hard on'.
"Q. What do you get if you cross an up quark with a down quark with a stange quark?
A. I'm not sure, but I think I've got a hardon!"

"Man, I've got a pure hadron."
by Team Baryon November 08, 2007