Dude, What Would Happen?/Fridge

• Fridge Logic: There's an episode where they try to figure out how to send text messages as cavemen. It starts off pretty hilariously: They write WTF on a big rock and fling it at a cardboard cutout of a caveman a short distance away. And nail Thog right in the stone quarry. Unfortunately, it goes downhill when they decide to send text messages in American colonial times, by writing messages on cannon balls. What's wrong with this picture? They already had a means of quickly sending signals over distances back then, using flag codes and semaphore (or, if you want to stick to actual text, by sending some guy with a letter from you in his pocket).