JAG's custom avatar is a special case afaik.

In the old days, the really old days, just a bit after the very ancient days when there were no avatars at all, just friendly posters. In the old days, there was no avatar choice at all for members, there was just a fistful of rankavatars. More post meant that you earned a new rankavatar. When you hit 1,000 you could get a special kensai avatar. This one was outside the ranking system and had to be issued by hacking some file. Pretty clumsy and it was often forgotten. JAG's avatar is the special 1,000 post ranking avatar with the SPAMMER banner, because he did spam a bit back then.