What could've the Towers done to not start 9/11?
Call 911.
Listen here, you smooth brain. The joke is that the Twin Towers could have prevented 9/11 by calling 911, which is the emergency number in the United States. Of course, they couldn't have because they are buildings and buildings can't call anyone. But if they could, they would have stopped the tragedy, like you could stop being a dummy if you tried.