The fun stream is moderated by Imgflip’s Community Moderators, and you have to be over 18, and i don’t even know if they’re looking for new ones. You can try posting in streams that instantly feature images, like MEMES_OVERLOAD.
You also have to have been on imgflip for two years, so there will be a few more months before you are able to get the role. I would suggest trying to get on good terms with global mods and stuff in the meantime