Community Moderators need to be adults with a good account history on Imgflip. There are currently three of us, we were all users for over a year and a half before it happened.
There isn't a form or an application, it's more like a path. I was an Imgflip user for over two years before I found a path to get there. I was in the right place at the right time, said the right things, had the right answers, had a good history with Imgflip helping the community.
These days it seems to me that it would be more likely that the path would open for the next user who becomes a Community Moderator, but I can't say for sure who it would or will be, or when it will happen.
