Multiple news sources have reported on a two-year microbiology study out of Rutgers University (Is the five-second rule real?). The upshot is: Yes, of course it’s not real.
What strikes me is that anyone actually thought it was real. We (meaning pretty much everyone I ever associated with) always understood it as a bit of obvious irony, a self-serving excuse for eating fallen food. If asked, I would have said one would have to be a real idiot to think it was real.
Well,… can’t say I’m surprised.