PROVE IT...

When Bubby woke up this morning, he jumped in our bed. We were playing "tickle" and he was cracking up. All of the sudden he says, "Wait, Mom. I think I need medicine." I said, "Medicine?" I knew he was trying to get me to stop tickling him. He said, "Yep, I need medicine." I said, "Bubby, you're not sick. You don't need medicine." He says with a huge grin, "Prove it." He's 2...where does he get this stuff?