What does it mean when someone is mega?

Excuse me, could you please clarify what you mean by "someone is mega"? Is this a slang term or jargon specific to a certain community? It's not immediately clear to me what context or meaning you're referring to. Could you perhaps provide some additional details or examples to help me understand the phrase better? I'd be happy to offer a description or explanation once I have a clearer understanding of what "mega" means in this context.