'Cause an erect penis, large or not, does not hang.
https://www.google.com/search?q=well+hung#q=define:well+hung
Also noting the OPs name and question combo. 
“Hung” means having a big pecker. Hard or soft hasn’t ever come into it, in any usage I can recollect.
Erect penises do hang - they just don’t hang down. (Usually.) They hang off the base of the torso, even if they’re pointed at the, uh, moon.
Yeah, it can refer to either state.
Additionally, a “grower” may not be hung while flaccid, but have an incredible increase in size and girth when erect.
It just means big, although I’d be more interested in the erect size. Some guys that look big soft don’t really get much bigger hard and a lot of guys that don’t seem all that impressive soft get huge.
That’s what David keeps telling me.
Yes, let’s hope David is a “grower”; otherwise he’s abnormally small, for someone who isn’t obese.
The Mediterranean Sea is just really cold, guys.
Yep. Hung means a great big ol’ floppy thing.
It should anyway. Lots of guys claim to be hung when they’re in the 7-7.5 range.
Hung - what a vivid visual. 
I’ve always associated the slang expression with a large penis in the natural hanging position.
Yes, that is the correct use of the word “hung”. You would use “hanged” if referring to an execution of a condemned criminal.
In passing it should be noted that there are those who are “hung like a mosquito” so it does vary. 
Whereas I bet you’re hung like a gorilla, eh? 
Yes, I know
In Classical Greece, it was a beauty ideal for younger boys to have smaller dicks. They were, after all, the receiving partner.
Another theory says The David is small because he shows fear of the fight against Goliath.
I hear Goliath was hung like a giant.
For a gorilla, I’d be freaking mammoth. (as would virtually any adult male of course…)
Hence the white text. 
Yes, I know.
What is this, a dick-measuring contest? 