Dropping the Bombshell

Alice and Bob are having a discussion on yesterday's football game when Bob mentions that his view was constantly ruined by "a mad woman jumping up and down in the seat in front of me". Alice asks about this mad jumping woman, and Bob tells her that she was a supporter of the other team, had a big scarf and looked like "some blond bimbo". Near the end of the discussion, Alice then reintroduces the subject, and Bob wonders why, whereupon she exclaims: "That blond bimbo was me!" Cue awkward silence.

Dropping the Bombshell looks at first sight like The Reveal, but whereas The Reveal is concerned with major plot points and can be expressed in more ways than words, Dropping the Bombshell is a conversational trope in which at least two characters are discussing a topic before one of them gives some surprising information to the other, usually bad or awkward information about said topic.

A good example is when one character talks about the subject freely, during which the other then secretly recognises something. Once the first character has said their bit, the other character will then give his or her information. The key to this is that the second character had the knowledge all along, but cottons on to the connection long before the first one does.

Can look like a form of Explain, Explain, Oh Crap, except that one character does the Explain Explain and then the other character goes Oh Crap. Usually, the character that did the Explain Explain knows the Oh Crap from the start, but since it doesn't affect them personally, they can be as relaxed about it as they please while the other character, having heard them speak, panics and tries to avert the incoming disaster. See also Wham! Line, which has the same effect at a meta level.

Anime and Manga
"Kouji: Your robot is great. What is its name? Tetsuya: Great Mazinger. Kouji: Great... Mazinger? Tetsuya: It's the "brother" of the original Mazinger-Z. Kouji: It is WHAT?"
 * Mazinger Z: Kouji and Tetsuya talk after :

Comics
"X-23: No. I lived here first. In the city. Gambit: Didn't know that. What were you doin'? X-23: I was a prostitute. Gambit: ...."
 * In X-23 #13, while traveling in New York Gambit asks Laura if she's "ever spent much time in this city?".

Fan Works
"Tsuruya: Would kissing be within those boundaries? Haruhi: I already did, so I'd be a hypocrite if I said no. Tsuruya: So he practiced with you! That's why he was so good .... Er.... Um....Um, I have a picture of me in a junihitoe on that SD card! Haruhi: You and him!? Er.... I mean.... Yeah, he's really really good, isn't he? Tsuruya: I thinks so. Yuki: I also think so."
 * In Kyon: Big Damn Hero, Haruhi and Tsuruya are chatting about Kyon and kissing in the presence of Yuki, who was silently reading:


 * It's an example because Haruhi and Tsuruya realize the fact Yuki and Kyon have been in a nightly Year Inside, Hour Outside training for the last weeks gave Yuki the chance of being kissed by Kyon many times before, even if he can't remember anything afterwards.

Live-Action TV
"You...are not...alone..."
 * The Face of Boe in the third season of Doctor Who sacrifices himself to free the inhabitants from the perpetual motorway, but survives just long enough to drop his bombshell

Video Games
"Sam Carter: A pistol is more than adequate. Hell, I dispatched a whole platoon one time with a pocket knife."
 * In Deus Ex, if you keep prodding Carter for dialogue, he'll drop this little bombshell:


 * Referenced and averted in Mass Effect 3. Talk to Tali on the Citadel  and she'll mention running into a turian clerk who she originally met three years ago, just before coming across Shepard for the first time, who was at the time quite rude and racist towards the no-name quarian. She says she considered revealing how they'd already met to make him squirm, then decided it would be beneath her, which Shepard says is a sign of virtue.

Western Animation
"Lawyer: The first time, it came back identified as ... rodent hair."
 * Ratatouille: Skinner reveals during a discussion with his lawyer that he is paranoid about the rat, thinking Luigi is trying to psyche him out. Skinner's lawyer notes that he had to take a second sample of Luigi's hair. When Skinner asks why, the lawyer says:

"Captain America: Now, when can I meet the Avenger who saved me from Zemo? The one in the black cat suit? Iron Man: Wait, who?"
 * From the The Avengers: Earth's Mightiest Heroes episode "Living Legend":