Supposedly Corn Pop is real
As I have a long personal experience with "story-tellers" like Biden, I'm going to assume that certain aspects of the story are true, but the vast majority of the story is wrong and biased in such a way as to make Biden look good.
Additionally, you'll notice I didn't say he was lying. I said he was wrong. He likely remembers the story in the way he tells it because he's the hero in every story in his own mind.