A mud pie is an equipableitem that can be worn in a player's main hand slot. It is because of this that the mud pie can be considered some sort of weapon, but it does very little damage and has limited uses (i.e. it is not stackable). Rather, it is thrown at other players to decrease their run energy by 50% (although it has no effect on NPCs). It can be obtained by looting baby implings or made using the Cooking skill. You will need to have level 29 Cooking to bake it, and will receive 128 Cooking experience from doing so.
After the Evolution of Combat update, players who wielded a mud pie would stand and walk in the same way as they did before the update. This was changed in the 13 April 2015 update.
An update on 26 February2018 made it so that mud pies drop to the floor when used to attack an NPC. Previously mud pies were lost during combat.