To simply be an idiot, arrogant, a self-proclaimed god. To talk down to someone. Someone that no matter what story you have to tell, they have done something that is bigger, better, and will ultimately be more than you did.
Person 1: Dude, we went to a dumpster fire the other day, wasn't much to it.
Person 2: Ohh yeah? Well we went to a dumpster fire. It was next to a daycare. There was fire everywhere. I rescued a hundred, no a thousand, babies during a flashover... everyone lived. And I did it all by myself.
Person 3: Man, you totally got Legged