Fool's Speech

With this spell, the wizard empowers himself and others of his choosing with the ability to speak a secret language incomprehensible to others. Creatures designated to speak the language must be touching each other when the spell is cast. Once cast, the characters can choose to speak normally or in their secret tongue. They can speak and understand this mysterious language fluently.
Fool's speech is not recognizable as any known language, nor does it remotely sound like any language. A Comprehend Languages or tongues spell will not translate it. It can be understood by a character wearing a helm of comprehending languages and reading magic, although the normal percentage chances apply.

[Tome of Magic]

School:Wild Magic
Magic Type: Alteration
Restrictions: Wild Mages only
Level: 3
Rarity: Uncommon

Range: Touch
Components: V, S, M
Duration: 1 hour/level
Casting Time: 1 turn
Area of Effect: Caster +1 creature/level
Saving Throw: None

Material Components:
a small whistle made of bone