Even when Rachel doesn't know what's going on, she's still the blabber-mouth. The rest of the Glee-clubbers are frantic because they're afraid she'll blow the "secret" to Finn. Because of course whatever Rachel knows, Finn will soon know. And Finn can't know. Because it would kill him.
So what do they do? Time for an emergency conference call. Watch this sneak peek from Fox for the fall finale of Glee - episode 13, "Sectionals.