A friend of mine gifted a sticker on which, "occasion genius" is written. I wonder what does that mean. I am not a native speaker, and I have really struggled to try to figure that out.
"Occassion Genius" is not a common English phrase. As a native (American) English speaker, it would look out of place to me, especially on a sticker; I would look to context to decipher the meaning, but would think one of the following things:
A grammatical error, which should be "occasional genius", meaning intermittent and infrequent "genius".
A corporate name, slogan, motto or advertisement tagline. As legal IP protections are more easily obtained for "abnormal" or "not commonly used" words or phrases, businesses tend to use "irregular" phrases for such things. (As an example, this is why IBM changed their name to their initials, away from their original name "International Business Machines").
A very unusual usage of "occasion" as a noun adjunct, modifying "genius" in a commonplace pattern used to indicate subject mastery. I would interpret this as meaning a declaration that one is a "genius" at hosting or planning occasions and/or events, especially formal events.
As others have said, it's not an English phrase with a recognized meaning.
As @sharur says, it could be a mistake, intended to say "occasional genius". That is, sometimes you have bursts of genius but most of the time you don't. That's the sort of half-compliment I'd expect to hear among co-workers.
Or maybe he's using "occasion" in the sense of "special event", like birthdays and anniversaries. So the meaning could be that you are a genius at organizing office parties.
If neither of those seems likely in context ... Is this a professionally produced sticker? I mean, something mass produced that many people would buy? Or did your friend make it? If it's mass produced, I'm stumped, because it doesn't make any sense. Is there any other information on the sticker, like other text or a picture that might give a clue to the meaning? If your friend made it himself, then it becomes more likely that he either made a grammar error, or that it has some specific meaning between the two of you that he thought you would understand.
Sorry that I'm not able to be much help.