They're just all over the place I guess.
I did this thing a couple nights ago where I changed some of the letters and numbers on the image search and I think 100% of the ones that came up were made by an anonymous user. Maybe that's what this kind of thing is.
Well I think it's imgflip itself that makes them. That's why they're not used and that's why all the images show up anonymous when you randomly search them.
I wonder why though... hmmm.... XD
Well yes it means that, but there are a TON of images made by "anonymous" and the ones I was mostly looking at had been made only a few hours before. I commented on all of them (cause I could XD) but no responses.