The yetis are everywhere, there may even be one in your house right now.

It's not a yeti "clan", but a clan of yetis.
There is no clan "tag" to use because you already identify yourself as a yeti in your name.
You may not roll with the yeti on all the time, and that's cool too. Just put the yeti in there somewhere if you want to show your yeti hide to the rest of the world. It may also look scary to the other team if they notice the opposition is stacked several yetis deep aginst them.