The son asks his father why there are so many different boxes of condoms.
The father replies, " Well, you see that 3-pack? That's for when you're in high school. You have 2 for Friday night and 1 for Saturday night."
The son then asks his father, " What's the 6-pack for? "
The father replies, " Well, that's for when you're in college. You have 2 for Friday night, 2 for Saturday night, and 2 for Sunday morning."
Then the son asks his father what the 12-pack is for.
The father replies, " Well, that's for when you're married. You have one for January, one for February, one for March, one for....."