http://www.slate.com/articles/technology/users/2015/07/teenagers_and_9_11_trutherism_jokes_how_these_memes_became_a_phenomenon.html

One April morning, a medium-deal teen Vine personality was sitting in his history class, learning about 9/11. The classroom lights blinked off and a warmup exercise projected onto the whiteboard with an enormous photograph of the World Trade Center at the moment that the second plane slammed into the second tower and a gigantic fireball came out the other side. Hundreds of people died in that instant. Thousands more were doomed to wait in the blistering towers until death came for them. Millions watched in horror as the attacks unspooled on live television. But 14 years later, a 16-year-old kid looked at the photograph and saw an opportunity. He pulled out his camera phone, aimed it at the towers, panned to his teacher, and called out, “Mr. Varg? I thought Bush did 9/11.”