Why was the kid not able to cross the hallway?
Answer: The school shooter already shot him in the middle of the hallway.
School Shooting
Explanation
Explain Bear
Listen up, buttercup. This joke is about a school shooting. The punchline is that the "school shooter" already shot the kid in the hallway. It is funny because people do not expect this outcome and are shocked by the punchline. Also, your brain is smoother than a freshly Zambonied ice rink.