Boy and Father in drug-store
Hey daddy, what are these?
-Those are condoms, son.
There's only three.
-Yes, son. Those are for highschool kids; one for Friday night, one for Saturday night, and one for Sunday night.
This one has six!
-Yes, those are for college kids; two for Friday night, two for Saturday night, and two for Sunday night.
Wow! This one has 12! Who are those for, daddy?
-Those are for married couples, son. One for January, one for February...