If I was a Mason I couldn't 'legally' spill the beans, but I'm not, and never have been, so I can in good conscience explain to those who think the question is related to their antecedents ........... It's not.

To find out if you are a member of a secret society called the Masons, a stranger will say to you, "Are you on the level ?" You, if you are also a member, will reply, "I'm on the square."

These are terms related to builders, or masons, a level and a framing square. To find out which lodge you belong to the questioner will say, "How old is your grandma ?" and you will give him your lodge number.

"Where does she live?" You'll name the location of the lodge. Keeps the riff-raff out.

In other words .......... nobody cares how old your grandma is or was ...........