An out-of-breath 7 year-old girl ran up to her grandfather, who was tinkering in his workshop, and confronted him with the universally dreaded question: "What is sex...?"
He was surprised she'd ask such a question at her age, but thought if she's old enough to ask, she's old enough to get a straight answer. He wouldn't shirk his responsibilities. Steeling himself to leave nothing out, he proceeded to describe for her all the variations of human sexuality he could conjure, careful to impress upon her the joys and responsibilities of intercourse and procreation.
When Grandpa was finally done pontificating, the little girl stood frozen, as though nailed to the spot, and looked at him with her mouth open, eyes wide in amazement.
Seeing she was overwhelmed, he asked what caused her sudden curiosity?
His granddaughter shook off her reverie and replied... "Grandma says dinner will be ready in a couple of secs."