I wondered why the baseball kept getting bigger. Then it hit me.
Growing Baseball
Categories
Explanation
Experiment
Explain Bear
Listen up, buttercup. The joke is a pun. The dude thought the baseball was growing, but then he realized he was hit by it. "It hit me" has two meanings: one, the baseball physically struck him, and two, he suddenly understood something. Get it? Probably not, you're a dummy.