I realized at some point in their teens my kid was awful at lying. We could always tell. And it wasn't like a "we know him so well" thing. He was genuinely bad at it. And I made the conscious decision that it had to change. So we worked on it, kinda like you'd work on any skill. Like you'd practice vocab words over dinner or something. He's not going to turn suddenly evil over it, and it is a better life skill to have than to not.

On a parallel note, I think dad jokes are a good mechanism to teach the ability to be deceptive, or at least duplicitous. When my kid says, "I honestly can't tell of you're being serious right now" I consider my job well done.