There was a boy who loved tractors, he knew everything about them, completely obsessed, he had tractor bed sheets, tractor wallpaper, tractor toys, anything to do with tractors, you name it he knew about it.
His father used to drive him around the countryside and whenever they saw a tractor driving around he would get really excited, "Look dad a tractor! It's a tractor!"
Then one day the father decided to treat the boy and took him to a tractor convention so he could see all the tractors, the boy was having the time of his life, sitting on tractors pretending to drive them, he had never had so much fun, then as he was sitting on the biggest tractor at the convention having a great time when the owner saw him and shouted "OI, get off of there now, it's a tractor not a toy!" So the boy gets off and has a glum look on his face, his father asks him if he wants to go and look at some other tractors and the boy just replies "No, I just want to go home." So they get home and the boy wants nothing to do with tractors anymore, he hates them, he throws everything out to do with tractors and never even thinks about tractors again.
A few years later the boy is grown up, he has a job and is living a good life, he's walking down the street one day with his father and there is a restaurant which is filled with smoke, turns out there was a malfunction with an oven and it is letting off an abnormal amount of smoke and nothing the staff do is helping there is just an overwhelming amount of smoke being let off, so the boy just walks in a sucks and all off the smoke in the entire restaurant just disappears into the boys mouth, the owner of the restaurant, clearly dumbfounded asks "How the hell did you do that?!" to which the father replies "oh, he's an ex-tractor fan."