This might not qualify as a fail, since the ultimate goal was to get some Internet recognition. But it's not really a "win" if you need immediate medical attention.
In the Vine below (uploaded to YouTube after the original was deleted), a guy attempts to pull off an incredibly risky stunt -- jumping over a speeding car -- but doesn't even come close to clearing it. At least he's able to jump high enough to not be run over:
He appears to be relatively unharmed in the ambulance, and the brush with death even seems to have given him religion:
Here I am sitting in the hospital, thanking God I'm alive. Thanking God for my stupidity, for my courage. Life is precious. Thank the Lord.
— Obi Nwosu (@brobii) September 15, 2013