How to make a command ask "You *really* want to do this?"

[David Combs]

I just discovered, to my horror, that C-x C-c does
a save-buffers-exit-emacs (I've always exited by
doing that "by hand", ie M-x save-buff...).

It was only via C-h l (ell) and then C-h k that
I discovered this (yeah, rtfm, David).

Anyway, I do like how C-x n asks if I'm sure that
I really want to narrow; I'd like to get
eg C-x C-c to do the same thing (requiring a
fully-typed-in "yes", maybe even two of them!),

Especially when it's late late at night, eg
4am, and I'm dead tired, and don't want
some knee-jerk <return> or "y", etc, to
result in a sometimes very-unpleasant surprise.

(Especially since (1) I tend to keep emacs "up" for
days at a time, and (2) I often keep various things
*scratch*.)

What methods do *you* use for installing such
protections-from-oneself?

Thanks

David