- “There, children. Do you see? Nothing good ever does come of lying. But the truth will set you free.”
- ―Lie Fairy
The Lie Fairy is a small fairy that comes to little boys and girls who tell "little white lies". Her purpose in life is to show them the value of truth.
The Lie Fairy first appeared in "The Imagination Situation". She appeared to Yin and Yang after the latter said he would rather look cool and earn respect than tell the truth. After Yang called the Lie Fairy "stupid", she cast a spell on Yang's toy robot Zarnot, bringing him to life. But instead of coming clean, the twins spread exaggerations about the coming of Zarnot. When the Lie Fairy found out, she cast another spell that would cause Zarnot to grow whenever a lie was spoken. She said that the only way to defeat Zarnot was by telling the truth. After Zarnot was defeated, the Lie Fairy appeared to the rabbit twins. But the citizens got angry with the fairy for the damage done to the city, and they chased after her in a mob.
The Lie Fairy later returned in "The Truth Hurts". She appeared after Yin lied about being on a guest list to hang out with a popular girl (which was actually Saranoia in disguise). Yang agreed to keep the Lie Fairy off of his sister's back in return for taking Lina out on a date. After the Lie Fairy saw through Saranoia's disguise, Yang and Lina rushed to help Yin before it was too late.