Where's "Tippy Top Secret" from?

[lilfluff]

Gah! This is driving me crazy. Somewhere I ran across a book where a character had something declared "Tippy Top Secret." I seem to recall that it was a female character, who was exercising some newly received authority. My sister (who has a good memory for this kind of thing) thinks I read her the scene around Summer 1997.

Now that it's popped into my head I'm going bonkers not being able to track down this reference. Even using google hasn't helped (why Google, why fail me now!), nor has using Amazon's book search, so apparently they haven't scanned whatever book it happens in.