When a person has to poop reallybad and they can no longer buy time by farting
Jimmy let out a string of farts in an attempt to relieve the pressure of his impending poop. He carefully allowed one last fart to slip out. Jimmy then knew that the next thing to exit his ass would not be flatulence. He was out of gas.
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!"