Ahh, I've seen users who have these tags in their name. During my first days of playing Feralheart, I would put the "M" or "F" mostly because I hadn't a clue there were bios to which you can store info about your charrie.. Perhaps that is why you may see quite a bit of that going on? There are many floofs who are quite new to the game, and as they familiarize themselves a bit with the game, they may put an end it possibly.. Though as Hugrf said, maybe they don't expect others to actually view their bios so they would want to assure everyone what gender their character is.
Feareh also stated a valid point that the "teen" tag is crucial in a few packs / prides. I've seen many with "pup" or "adult" at the end of their names as well, though it doesn't particularly bother me much. Some have just grown into a habit of acquiring those specific tags in their names, nothing more and nothing less. As stated above me a couple of times, since it is their own character, they should be able to name it whatever they want {well... appropriate names of course}.