The line comes from the world of Little Brown Bear, the children's cartoon about a young bear whose stubborn, spoiled behaviour often frustrates viewers. Online, that frustration became part of the joke, with fans clipping short outbursts and sharing them as reaction sounds rather than episode clips. Its tiny length helped it spread on soundboards, where a single tap could answer an insult or a selfish act. It remains used because the delivery sounds sincerely offended about something trivial, a contrast that still fits modern meme edits.
About this sound
A short voice clip shouting you're so horrible, really horrible, from Little Brown Bear. Used as a dramatic reaction to rude, bratty behaviour.
It is a very short shouted insult, you're so horrible repeated with extra emphasis the second time. The voice sounds young, upset and deliberately over the top, like a child having a tantrum after being told off or denied something. Because it lands in under a second and ends abruptly, it feels more funny than genuinely mean. Listeners hear instant melodrama, which makes even a small annoyance sound like a huge betrayal, and the repetition gives the line a whiny, bratty edge that sticks in the mind.