kidding

probably from

verb

  1. to deceive (someone) as a joke : to say untrue things to (someone) in a playful or joking way

  2. to fail to admit the truth to (someone)

  3. to gently criticize or tease (someone) in a friendly or good-humored way

It's the truth; I wouldn't kid you.

They're kidding themselves if they think they can win.

verb

  1. to bring forth young —used of a goat or an antelope

idiom

  1. —used when someone says something surprising or that seems as if it could not be serious or true