Arizona Bob nails it.
I was an officer of a Mensa Local Group from around 1978 till 1983. My official title was Editor, but in reality Communications Officer would have been more accurate.
In a rural state, we had more meetings a month than most big cities like LA. The newsletter either made or broke the Local Group, and in our case with some good writers we made it.
You people who made childish comments about Mensa people being snobs should know it's always a bad idea to write about something when you know nothing about it. Shame on you. If you don't want to join, don't, but don't make stuff up.
One of the standing jokes in Mensa is qualifying for Densa, the bottom 2% of the population. Years ago, the national magazine had an article from a woman whose kitchen sink trap broke. So, while she waited for the plumber, she put a pail under there and went on with her work. When the bucket got full,
she emptied it down the sink! 
There would naturally be snobs in Mensa, just as there is every other kind of person, including prison inmates. But, except for a very few unpleasant individuals, it is not a snob organization.
Most of our new members joined merely as a lark. They mostly imagined it was a fluke and hesitated to go to a meeting with all those "smart people." I sent all new members a hand-written note, which was designed to look like a personal letter, though it was a pre-written form letter. In it, I would say as editor any mail in my mailbox would be considered for publication if it was suitable. And, I would basically introduce them to Mensa and our local group.
Many would send me a nice response, and a week later when they got the newsletter, their letter would be on the front page. Hey, it worked! Nothing works better than attention. They would come to a meeting, and like it, then they'd have their own meeting. Most meetings were held in private homes, one regular meeting was held in a small restaurant in the town which had the State University, but thus I ran the newsletter to suit the blue collar and middle class folks who had houses for meetings. Most meetings were social, a lot of intellectual talk much like the technicians in the factory where I worked, sometimes slightly risque talk, always stimulating. In private homes, there was not much excess drinking, but most were BYOB. If a meeting was no-smoking or involved religion, it would be plainly stated. One of my writers was an old retired pastor, who used to write fascinating stories about his youth.
Many Mensa members in those days would go into a period of self-analysis. They would ask themselves the question, "If I am so smart, why aren't I more successful?" Many would go back to school, or changed careers. My best writer took writing courses, and left her job to become a tech writer. A few years ago, she contacted me for her poems which I had printed, to add to a book she was producing.
Then, they dropped out of Mensa.
Mensa would never state an opinion on euthanasia of children. I bet there was actual violence when those idiots printed that opinion.
Mensa used to have local proctors to administer tests, probably still do. The national can give you addresses. There are indeed several tests the proctors give, and one can use different tests. I used my Army GT test. Since there are a number of tests, some based on logic; others on verbal and written word skills, others on patterns, etc., actually they accept more than 2% of the population, since iq. comes in different flavors.
Isaac Asimov was a lifetime member until they refused to do something he thought they should. Wayne Green, who used to publish a ham magazine, was also a member.
Mensa has SIG's, special Interest Groups. You can start your own, and it will be publicized in the SIG brochure. I would be surprised if there is no Treasure Hunting SIG, but do not know.
I dropped out when I resigned as editor, so I would not "walk on" the new editor. A few years later, I rejoined one year, but not again, because it had the same PC and gender politics as society, something I did not permit as editor.
Local Groups will vary depending upon the officers of the moment.
My favorite memory had to do with three kids who joined about the same time, from a small rural town. I knew there had to be a story, and wrote them for an explanation. Two girls and one boy, very smart, and very intellectual discovered each other very young and became friends. After high school, all three became foreign exchange students and used to write letters from their countries, which I printed and were much enjoyed by the members. They were neat young people. It's hard to imagine they are in their late 40's now.
We had a newsletter exchange program, and I used to get Rue-minations.
) Is nudity involved? 
?
