The key to executing a Hadouken in real life is beating the current record for fastest dodgeball throw.
Students of the University of Leicester's Department of Physics and Astronomy investigated just how average humans like ourselves could create a Hadouken-type fireball, a special attack used by certain Street Fighter characters. The students, A. Toohie, J. McGuire, and A. Pohl, discovered a way - unfortunately, their conclusion indicated their method is currently impossible to execute.
The students' method included soaking a dodgeball in gasoline and throwing it fast enough for it to so that the viscous drag forces would ignite the fuel. In order for the fuel to ignite, a person would have to throw the gasoline-soaked dodgeball at 93 miles per hour. The current fastest dodgeball throwers can throw a dodgeball around 66 miles per hour. Even if someone could throw a dodgeball at 93 mph, the students concluded even this wouldn't be enough.
"Even if we assume the player could still throw as fast with a gasoline-soaked dodgeball as with a normal dodgeball," the students concluded in their paper, which was published in the Journal of Physics Special Topics, "they would not be able to attain this autoignition velocity even momentarily, and as such could certainly not maintain it for any length of time, as would be required for the ball to ignite."
It may be impossible for a human to throw a dodgeball with the required velocity, but mechanical launching methods could provide a solution. Perhaps we were not meant to master the Hadouken.