Robin recently learned how to make a cootie catcher. I explained to her that, when I was her age, they usually had colors on the outside, numbers on the inside, and a message under the flap.
I don't remember the rationale for 5 - probably Julia's age.
7 "Because it's Lisa's favorite number."
37 "Because that's how old you are, Mommy."
42 "Because it's the meaning and purpose of life."
Clearly, my work here is done.