That's what Lily always says when she falls down, whether it's off her bike or while walking down the street. We'll see her go down and then hear, "I'm OK!" It cracks us up.
Here's Lily after deliberately falling off her bike into the grass. It's what Lily does instead of using her brakes. Campbell was making sure she was ok.
And here she is cruising down the street, with the biggest smile. She's so proud that she learned to ride her bike.