Teen music/acting starlets Miranda Cosgrove and Victoria Justice will take the same stage when their respective Nickelodeon shows, 'iCarly' and 'Victorious,' are impounded into one spectacular mash-up ...

That's when Dan chimed in saying he's MORE than down for the cause. Basically, every single person on the Victorious cast as well as its creator (who's created, like, eleventy million successful shows ...