3. an ill conceived plan that has no chance of coming to fruition
4. something that does not exist in the real, or physical, world
Geezer: …so this “crypto currency”, as you call it, which doesn’t exist in any physical form, is going to revolutionize the way the world transacts business?
Millennial: Yes…exactly.
Geezer: That’s just a unicorn fart in the wind.
A door wall is a sliding-glass door or patio door. The term is yet another example of banal Michigan vernacular, where in the residents latch on to company names, trademark names, marketing terms and product names from local companies. The terms become embedded in the local vocabulary and eventually become accepted as actual valid words and phrases. In this case the term comes from Wallside Windows in Taylor, MI (a large window manufacturer), where 'door wall' is their created word for sliding-glass door.
"Bob! John's gonna bring over them doorwalls from Wallsides on Tuesdee afternoon 'round two-thirty. Get 'er done!"