What did you think sex was before you learned what it actually is?

When I was about 7 or 8, I was with my sister and cousin who were 8 years older than me. They were gossiping about kids at their school having sex. For some reason, the mental image I had was of one of them jumping on the bed while the other one was swinging from the blade of a ceiling fan into the bed jumper's arms. Both of them were dressed in pajamas. I had a vivid imagination.