Lemme just get this straight. When I discovered this glitch I did not intend to do this with my thumbnail. From what I know, this only works on iPad. Do not report me for finding a glitch. You can't abuse this glitch. Basically, to do this glitch you need ibispaint. Go onto ibispaint with your avatars and erase the entire background. This will make your thumbnail transparent! If this gets patched, I'm not too bothered as It means the community is less glitchy. ?
