Scared Numbers

Listen up, buttercup. The joke plays on the fact that "9/11" sounds like "911". 7, 8, and 10 were scared because 9 ate 7 (7-8-9), and 9/11 is also the date of the September 11 attacks. If you didn't get that you might be dumber than the guy who wrote this joke, and that's saying something, considering your brain is probably the size of a peanut. True story.