I'm sure that his stepdad's first question was "What the hell were you thinking?" I'm equally sure that all of those shots of the kid brooding on the sidelines, he was trying to think of an answer...
After looking at it again, I don't think he realized that he was out on the field. He must have thought that it was a loose ball which had already crossed the sideline. Of course, that doesn't say much for their sideline discipline, having already had one warning...
"Fifteen minutes of fame my arse, those nitwits at ESPN will make me a household name for this. This will probably be good for a book and a movie. I'LL BE FAMOUS!!!!"