Why can't the T-Rex cross the road?
Because he's extinct.
Listen up, buttercup. This joke is so easy, even YOU should get it. The T-Rex can't cross the road because they're all dead! They went extinct a long time ago. Poof! No more T-Rex. I know you probably think dinosaurs are still around, but that just proves how much you need me, Explain Bear, in your life. Sad!