Idiotic Partner Confession

"Shenzi: Do you know what we do to kings who step out of their kingdom? Simba: Phuh! You can't do anything to me! Zazu: [nervous chuckle] Technically, they can. We are on their land... Simba: But Zazu! You told me they were nothing but slobbery, mangy, stupid poachers! Zazu: Ix-nay on the upid-stay... Banzai: Who you callin' upid-stay??"

- The Lion King

Idiotic Partner Confession is a situation in which X is keeping something from Y, be it a something he's done, something he's planning, or just something he said earlier that he really doesn't want to tell Y. The problem is, Z is also aware of this secret, and just happens to be a complete idiot. So what does Z do? He starts talking about it right in front of Y, if not directly to him, of course! This will undoubtedly lead to X trying as discreetly as possible to get Z to shut up, with Z completely oblivious that he's saying anything remotely wrong. This will likely piss Y right off, and lead to all sorts of trouble for poor X.

Y can either be a villain, some sort of parental figure, or anyone else who X would have any reason not to be honest with. Z doesn't necessarily be an idiot to do this; it could very well be a case of Will Not Tell a Lie.

Different from Right Behind Me, although the tropes might overlap. Compare Accidental Public Confession.

Anime and Manga

 * Yukari from Girls und Panzer is hardly an idiot, but she otherwise matches this trope when she mentions to her teammate Hana's mother that Hana is her teammate - Hana has not mentioned that she'd joined the school's tank club.

Film

 * Simba does this in The Lion King, when he questions why Zazu is acting so afraid of the hyenas when he said earlier that they were "slobbery, mangy, stupid poachers". Said hyenas are, of course, right in front of them.
 * Not completely played straight, since Simba wasn't so much an idiot as an innocent child, and Zazu teaching him to be racist was a bad idea in multiple ways.
 * A second example later on, when Mufasa corners the three Hyenas after they tried to kill Simba. Shenzi and Banzai immediately insist that they had no idea Simba was Mufasa's son; then Ed spills the beans.

Live Action TV

 * London Tipton does this in an episode of Suite Life on Deck.

Web Comics

 * This Girl Genius strip. Dimo succeeds at knocking out Oggie before he's entirely spilled the beans, but Zeetha isn't fooled.

Western Animation
"The Flying Dutchman: Who be disturbin' the Flying Dutchman in his own lair??? Spongebob: It's Squidward. He wants to complain to you. Squidward: I-I...No, I...no. Spongebob: But what about all that stuff about him having a dirty ship, and being lazy, and all? Squidward: *laughs nervously* I never said that... The Flying Dutchman Insulting a man's ship is worse than insulting his mother! Spongebob No wait, maybe it was his mother you said was dirty..."
 * SpongeBob SquarePants does this to poor Squidward when they're faced with the Flying Dutchman.