There are real cowboy sayings:
"He's all hat and no cattle" means a guy is all talk and no action.
When something is going nowhere, it can be described as "that's a dog that won't hunt".
These are old sayings. But I used to make up sayings right away that sounded like old cowboy sayings, but actually just came out of my mouth. I used to make them up right away.
- "That's a three-legged chair on a four-legged floor".
- "He's packin' a beer for a wine tasting".
- "That old horse been ridden hard and put away wet".
- "You can't load that in my pickup truck".
- "You can seed the back-40, but that crop ain't gonna grow".
- "You're driving a Ford in a Chevy town."
These are meaningless phrases. They say nothing at all and don't have any relevance to the matter at hand. But people all over the UK bought them as sage country wisdom (even though I come from the city and have never lived in the country).
It was great fun.