One night when i was around 16 years and the whole family lived together, a old friend of mine and me had a few drinks.
Very late at night he went for a piss but didn't return. I was thinking he was drunk and went home.
He showed up again what felt like two hours later and i was surprised.
That bastard knocked on my sister's door because he saw light and turned out they made out.. what a dirty laugh he had..
He is not my friend anymore tho for several reasons. My sister is happily married now.
Don't think too much when you're young and it tickles between the big toes, just never forget protection.