Promuse

promuse
/ˈprɒmju z/
/pro-myuze/
noun

1. a false declaration of assurance that something will surely happen or someone, usually themselves, will surely do something.

verb

1. to falsely assure that something will definitely occur, or will definitely be done by someone, usually themselves.

Promuse is intentionally misspelled to make it look as if you're trying to say promise, but since the definition has been set to a lie, you're no longer lying and you can now assure your friends that you "promuse", while you don't really promise something and you don't lie either.

Person 1: "I don't believe you! Promise me."
Chad: "Okay, I promuse."
Person 1: "Alright, I believe you."