What is the Extractor Fan joke?

There was once a man who adored tractors—I mean, he adored them to the hilt. He had tractor board games, tractor models, tractor wallpaper, remote-control toy tractors, and even some tractor erotica (which is difficult to locate, mind you). The love he had for his wife was the only thing that even came close to matching his passion for tractors. His high school girlfriend, who was unfazed by his obsession with tractors. She didn’t even mind the role play where she would dress as a tractor, he would dress as a farmer, and he would take her for a “ride”. Sadly, a tractor toppled off the back of a transport truck one day, striking his wife. She passed away in the hospital and told him, “Don’t hate the tractor.” But he did. He got so mad that he burned all his tractor stuff (even the p*rn). Anything that didn’t burn well enough for him was put in a woodchipper. He then returned inside and stayed there for the next eight years.
After eight long years, he finally made the decision to resume dating on the eighth anniversary of the passing of his beloved wife. In addition, the hot cashier at the grocery store had been wooing him for some time, so he decided to invite her out to dinner. He ultimately picked a fantastic restaurant with good food, excellent service, and lovely decor. However, there was one issue: it was VERY smokey. It was so smokey that his date, who suffers from asthma, had difficulties breathing. He began breathing in after he noticed her irritation and difficulty breathing. He then began to breathe. Really breathe in. He inhaled so forcefully that all the smoke from the dining room immediately departed and entered his lungs. He stepped outside and discharged it all into the night when the room was smoke-free. She questioned him when he got back with his date, “How on earth did you do that?”
To which he replied, “I’m an extractor fan.”