Our 4-yr-old tells the same jokes over and over. To humor him, we usually pretend we've never heard them before. One day, he told a Silly Billy joke for the umpteenth time to his dad:
Josh: “Why did Silly Billy throw the clock out the window?”
Dad: “I don’t know. Why?”
Josh: “To see time fly.”
As his dad laughed, Josh shook his head and said, “That one ain’t that hard, Daddy!”