I broke a player's brain in college playing DND where an NPC just lied to her.

She'd asked where so-and-so was. NPC didn't like her or her faction, so he just lied and said he'd taken up boxing. This isn't an especially credible lie because so-and-so was a lightweight nerd. But she says okay and goes tearing up the local boxing clubs, and can't find the guy.

She's like "where is he?"

Me: "you don't see him, and no one's even heard of him."

Her: "but the guy said he was here"

Me: "he did"

Her: "so where is he"

Me: "doesn't look like he's here"

Her: "but he said he was"

Me: "he did say that"

Her: "so why isn't he here?"

This went on for a while until one of the other players got impatient and said "the guy who doesn't like you maybe lied to you! Or was wrong! Can we move on please??"

"For those who come after"?

Because it is hard to convey a lie through story, unless blatantly saying it was a lie afterwards.