Why condoms comes in box of 3,6 and 12

WHY CONDOMS COME IN BOXES OF 3, 6, AND 12

A man walks into a drug store with his 8-year old son. They happen
to walk by the condom display, and the boy asks, "What are these, Dad?

To which the man as a matter-of-fact replies, "Those are called
condoms, son. Men use them for safe sex."

"Oh I see," replied the boy pensively. Yes, I've heard of that in
health class at school." He looks over the display and picks up a
package of 3 and asks, "Why are there 3 in this package?"

The dad replies, "Those are for high school boys, ONE for Friday,
ONE for Saturday, and ONE for Sunday."

"Cool" says the boy. He notices a 6 pack and asks, "Then who are
these for?"

"Those are for college men," the dad answers, TWO for Friday,
TWO for Saturday, and TWO for Sunday."

"WOW!" exclaimed the boy, "then who uses THESE?" he asks,
picking up a 12 pack.

With a sigh and a tear in his eye, the dad replied, "Those are for
married men. ONE for January, ONE for February, ONE for March....."