Translation: "Oh my goodness, imagine something as crazy as that!"
Used when a person preposes a crazy idea or when someone does something really stupid. It's an addictive phrase.
1: "That guy looks like he's gonna jump over the counter and hurt me..."
2. "Oh yes, Imagine he did and I bit him!"
Person B falls in the parking lot in front of his friends, gets up, dusts off, and says "Oh yes, imagine I never learned how to walk!"