Poison joke is an infamous flower that grows in large patches throughout the Everfree Forest, easily identified by the bright blue colour of its leaves. As described by Zecora, "That plant is much like poison oak, but its results are like a joke." Poison Joke likes to play pranks on any creature who comes into contact with its leaves, causing that creature to develop ironic physical effects. For example, a fast pony may become very klutzy or a pony that likes to talk may find themselves mute. Those affected by Poison Joke are usually easily identified by the bright blue spots that normally appear in relation to the affliction the creature suffers.
The cure for poison joke is a bath in water mixed with an added natural remedy. The remedy is composed of certain herbs, plants, and flowers also found within the Everfree Forest.