I am Beowulf! - A line that people say when they think they're the best but

A line that people say when they think they're the best but they're really just average.

'I am Beowulf!' he said, even though he had a D in math.

'I am Beowulf!' she said, because her dog ate her homework.

'I am Beowulf!' he said, because he thought he was in a video game.