"Someone said" is a great way to introduce stuff that you want the listener to think is true, but which the narrator knows to be false. Variants include "Everyone knows", "According to X", and "It's common knowledge that". You can see it in action in the early Harry Potter books, which have a bunch of "Everyone knows" statements about Professor Snape.
You can learn some great GMing tricks from narrative tricks in literature. Keep an eye out for them next time you read a novel.
GM: While you're still thinking of a decent plan, Luke arrives.
Luke: So what did I miss? Anything about the new Peace Moon?
Leia: Well, yeah. How did you know about that?
Luke: An old... friend... told me.
Chewbacca: Mon Mothma has briefed us. The Moon is orbiting Endor, the moon of Endor.
Luke: That's confusing. There has to be some other explanation.
C-3PO: She said our best spy, Wedge, died to bring us this information. But—
Luke: Wedge? Died?? Hmmm. Wow, I guess he wasn't such a bad guy after all.
Wedge: Actually, I'm still right here!
Wedge: Hey good buddy! Long time, no see.
Luke: Wedge! Um... Wow. You may be a shapeshifter, but hey, you're all right by me.
Wedge: Well of course I am, good buddy.
C-3PO: You don't have to be human to be a person.
Han: Yeah. Some of my best friends are shapeshifters!
Han: Well, for all I know.