First, don't tell anyone. No, not even if you tell them not to tell anyone. Secondly, don't seem as if you
have a
secret. Thirdly if you have to talk about it, don't lie if you can simply omit
information, and don't omit information if it's not The
Forbidden Knowlege itself, the person has some
need to know, and they ask specifically. Most times, people are less curious than you think. Case in point:
I used to be a member of the OTO (my membership lapsed some time ago, so don't ask me about it.) My sponsor in the group was a kid named John Smith (no lie!) whose entire being shouted "HEY! I'M A MEMBER OF SOME WEIRDO SECRET SOCIETY, AND I'M NOT TELLING YOU ABOUT IT!" That is, he wore sunglasses, had a Van Dyke beard (before it was popular), and long hair, wore heavy silver jewelry, and cultivated various Hoochifoo accents. He also slinked (slank?) a great deal. It would be different if he wore black, but he preferred denim with all kinds of arcane patches. A real winner.
Me, I was a semi-preppy looking bookstore clerk. He repeatedly told me NOT to talk OTO to any "profane", and mostly I didn't. That is, other than occasionally answering "Yes, I'm from the Bavarian Illuminati. How may we help you?" to off-the-wall questions at the shop.
Midsummer Night approached, and we decided to hold a working. I was to get the flowers from the local grocery-store florist. After the usual lecture on discretion, I walked up to the counter, and began the order "Four bundles of yellow roses, I'd like to pick them out myself, four red roses..."
The florist person began to pack up the order. "This is pretty big. Any occasion?"
"Actually, I'm with a small religious fraternity nearby...we're having a Summer Fest, and..."
"Oh, how very nice. Got your tax-exempt card with you? No? Well, I'll just ring it no-tax anyway. So nice to see young people getting involved..."
I brought the thorny bundle back to our Camp.
"How did it go?"
"I just told her it was for a fraternal religious group, and didn't say who."
"You dolt! People don't join those things anymore."
"We did."
I get the feeling that if he'd handled the order, the florist would have called the cops....