Sex, in its clearest definition for a boy as he grows to be an adult.
- At four years old: it simply is a mispronounciation of "six"
- At seven years old: an unclear definition, but he has heard the word
- At ten years old: It's what mom and dad talk about occasionally. He wonders what it is.
- At thirteen years old: It's what he and his friends are all talking about and curious to try.
- At fifteen years old: Really wanting to do it with a girl.
- At eighteen years old: Probably has already done it with a girl, or he is considered a loser.