adjective - of a food, having the property of increasing the production of intestinal gases. For example, cabbage, chili beans, lentils. The noun form is 'flatogen'
Dude, why'd you have to eat that chili bean burrito for lunch? Don't you know it's flatogenic? You've been farting every five minutes for the last 100 miles of this trip!
When a meat-head or bro tackles a smaller person so that he can violently rub his head on their head. The purpose of the flat dog may be homoerotic in nature.
Sean, stop flat dogging Kyle. He's about to cry and you have a Texas-sized erection.
It is said of the situation where a person has the bad luck to make contact with his testicles against an undefined surface or object, intentioned or not.
Given the nature of the word, it is more appropriate to design cases where the interaction is made with a moving object, for example, a ball.
Although it is extremely painful for the victim, it tends to be considerably funny to people who witness it.
Today in the baseball game the pitcher took a nutshot; the baseball hit him in the nuts.
Man, I just watched the funniest nutshot video ever.