Considering membership is open to folks who test in the 98th percentile... there are probably quite a few SOS members who could get in. That correlates to a 132 IQ.
There are about 100,000 members of Mensa.
However... I am pretty sure that only Nick could get in the Triple Nines Society, made up of folks who test at the 99.9 percentile. There are only 1,000 members of Triple Nines.
There are about 465,000 people in Mesa, so that is probably easier to get into than both of the above.