There are a series of posts on Stack Overflow about some unknown secrets for every major technology (C#, Java, HTML, etc).
Does anyone know where these questions can be found?
We keep those tucked away in a very safe place, just to be sure innocent passers by don't unwittingly get sucked into them. The video feed from the warehouse is a little fuzzy, but here's a shot:
Why? Spaghettification hurts, so you'll need to sign a waiver in order to read these. Currently, the only way to do this is to earn at least 10,000 reputation points which allows you to see deleted content.
In all seriousness, these questions fall straight into the chatty, open ended category of things we'd rather people not ask. You'll find most of them deleted, as they tend to become trampolines (or evidence that such questions are appropriate) even if closed, locked and clearly labeled as problematic.
What you're looking for are the Hidden Features of _________ "questions". They're generally closed, locked or deleted as they aren't appropriate questions for Stack Overflow.