A dog will crawl on its belly to show submissiveness to another dog. Presumably crawling in the dirt leaves a yellow stain on the belly.
My coat of arms, resplendent with chickens. Note the motto: “Ne Lis,” latin for “no strife.”
I had always assumed that yellow belly had something to do with urinating out of fear, but I don’t know that for sure. For what it’s worth, the Word Detective said this about yellow.
I agree. “Chicken” should mean stupid. Or mebbe that should be reserved for “cow”.
Sheep are more stupid than cows, though.
And I’ve always found it greatly amusing that the University of Delaware has a literal yellow-bellied chicken as a mascot.
Staff Report by Dex: What’s the origin of “yellow-bellied”?
Those aren’t chickens. They’re cocks.
Well probably one of your ancestors ran from a fight and that’s how the chicken got the bad name.
(just kidding, but it may be something like that)
Did you use a cartoon as a reference? 
This is an example of what these hu-mans call “humor”. It is a…difficult concept.
Oh OK. I couldn’t see the tongue in cheek. :smack:
I think it’s proof that Intelligent Design even reaches linguistics:
The whole thing was to set up the Bluth family’s impressions.
Domestic turkeys are stupider than sheep. My father had some that drowned because instead of going inside of their coop when it rained, they stared up at the sky. Water ran down their noses and filled their lungs, drowning them.
Snopesdisagrees:
I guess furubafan74’s dad’s turkeys didn’t read Snopes. Imagine the tragedy that could have been prevented if only they knew where to verify the barnyard rumors they heard…
Hey furubafan74, why don’t you make like a drum and take a hike!
MOIDAZIZE We’re in General Questions. I’m not sure what you’re trying to do, but it doesn’t have a place in GQ.
samclem Moderator, General Questions
Why not? People certainly had farms back then, and according to Wikipedia, chickens were first domesticated “over 10,000 years ago” (in Vietnam apparently), and were introduced into Europe in the 5th century BCE (and I think that is probably a latest possible date, not an earliest).
For what it is worth, when growing up in England in the 60s and 70s I do not think I ever heard “chicken” used to mean “coward” except in American movies and TV shows. If it is used in Britain now, it is probably because it has been picked up from these American sources. It may well be that it goes back much further in English, but perhaps it was a rare or moribund idiom that somehow got revived in America some time in the 19th or 20th century.
It’s just a flesh wound.
(1975, by the way)
Ok so it made its way into British movies a bit earlier than I thought. That doesn’t prove it didn’t come in form America though.