The enchanted lamb egg can be won from Treasure Hunter. It can be activated to turn the player into a lamb for 5 minutes. Unlike its magical counterpart, the enchanted lamb egg is not consumed when activated. The egg was made available from Treasure Hunter again from 2 April to 7 April 2015.
The egg cannot be used in PvP areas. While transformed into a lamb, you cannot move in this form as if you do try to move, the players character will turn back in to human form.
Other players cannot right click on you. You do show up in the right-click menu if another clickable object is on the same square, however.
Treasure Hunter eggs