This one was inspired by Stephen King's recent novel 11/22/63
Insert a scene around this bit of dialogue - the dialogue itself can be anywhere in your piece: beginning, middle, or end. I won't tell you who the characters are (except for one, which is obvious at the end) so play around with different roles, whether it's a psychiatrist and a patient, a bartender and a patron, or two strangers on a train.
"Need to get something off my chest."
"Certainly. I'm all ears."
"Keep in mind, I've never told anyone this before. Not sure why I'm telling you now, but here it is. I . . . I killed the President."
"Huh? I don't understand. Which one are we talking about?"
"Can't be Lincoln, you dumbass! It's Kennedy, who else? And before you go asking, I'm not this supposed second gunman on the grassy knoll. That's total conspiracy theory bullshit."
"Buddy, I hate to say this, but the guy who killed Kennedy is dead. Lee somebody. Never was any good with history, but I know his name was Lee."
"His name was Lee, but the guy who was killed was an imposter."
"Come on, now. You're telling me all of the history books are wrong-"
"We're getting off on the wrong foot. Let me introduce myself. I'm Lee . . . Harvey Oswald."
**One may think this is impossible, but stretch your imagination for a bit and think of how Charles Dicken's A Tale of Two Cities ended. Hmmmmm . . .