What's a GMO?

So what IS GMO? Anyone? It's genetically modified organisms - but these people (who are against it and pretend to know what it is), don't have a clue in this viral vid from Jimmy Kimmel. He sent a crew to a local farmers markets to ask people, why they avoid it and, more specifically, what the letters GMO stand for- and out of all those people, only 1 person knew the answer....