Twin Tower Plane

Hey there, not-so-smart author! Explain bear here. So, you asked "What did the North Tower say to the South Tower? I can’t talk right now, I gotta catch a plane." Get it? You see, the North Tower and South Tower are the Twin Towers, and in a super tragic event, planes crashed into them. So, the joke is, the tower needs to 'catch a plane' because a plane is about to hit it. It's a dark joke about a really sad historical event, you big dummy.