Obnoxygen is a pungent, invisible gas that is created by Donny when he behaves obnoxiously. The gas is poisonous to Why-wolves. Without Obnoxygen, the Why-Wolves terrorize the House People. Even though the House People do not enjoy Donny's presence, it is necessary for their survival. It is unknown whether all obnoxious grass ogres emit this gas, or only Donny.