REPRODUCTION
birds and the bees
human reproduction. (A euphemistic way of referring to human sex and reproduction. Fixed order.)My father tried to teach me about the birds and the bees.He's twenty years old and doesn't understand about the birds and the bees!
the facts of life
the facts of sex and reproduction, especially human reproduction.My parents told me the facts of life when I was nine years old.Bill learned the facts of life from his classmates.