User blog comment:TheNewProtagonist/Vol. 2 Episode 1 - I just.... why?/@comment-4010415-20140727041746/@comment-4010415-20140727164524

Well, aura acts as a shield to absorb/block a large amount of damage that's inflicted on someone. Though, it was kind of dumb of them to waste their aura on a food fight. I think after all that training, they were like "Let's wreck shit just because we can! YEH, we have SUPA POWAS!" Kids do stupid shit, thinking they're invincible, even in our world.

Also, it was meant to be a stupidly silly scene, so there's also that.