Inexperienced student group of eldritch enthusiasts just accidentally summoned her while joking around with some ritual... None of them believed it would work and they just made it into a video... drawing a giant sigil on the ground and calling her name... one of them accidentally pronounced it correctly and her giant figure showed up... all of the students panicked seeing her, but none of them dared to run, as they were not stupid enough to believe they could...

Cthulhu: Wow, you guys have made a whole club about me? That's adorable!