How do you be a sheep in castlewars in RuneScape?

Wear something of another God while entering a Portal. For example, if I entered the Saradomin Portal while wearing an Unholy symbol of Zamorak or Unholy Book, I would get turned int oeither a Bunny Rabbit or a Sheep. The same goes for Zamorak, except that I'd get turned into an Imp. Even though Guthix has no team, you can get turned into an animal if you wear something of another god while going through the portal.

Source: http://runescape.salmoneus.net/castle_wars.html