Although, this doesn't mean you zapping someone with enough lightning and they can become the flash. The electroporation process is one way of damaging the cell just enough to make them take in foreign DNA. Think of it like poking holes in the cell and DNA got in. Whether that DNA get recombined or not depends on other processes, which might also get activated as a stress response to the damage. But it is entirely random. So the DNA coding that specific function/protein must be available in the environment first, and the cell must survive the process of getting struck by Zeus and be lucky enough to do the recombination just right to retain that piece of DNA to produce a proper mutant.
Lots of entropy here, like someone said elsewhere. But that is life. Do it enough time and maybe something fun come out of it.