A childhood belief about swearing

Well it isn't really my belief but a couple of years ago me and my best friend were having a conversation, aware that my little sister was listening outside and would pick up anything we would say and apply it to her everyday language. My friend said the word 'f***' and from outside came a little gasp of disgust (hehe) and then i explained to my friend (loudly so my sister could hear that it was fine to say 'f***' because it was merely a ''naughtier'' term for sex.

Of course my sister isn't stupid (!) and she obviously knew that to tell someone to 'f*** off' was wrong. So a couple of days later my best friend and I were watching TV and down came my little sister who was going to go out with my mum. Now, my mum and my sister never get on when it comes to what type of shoes are appropriate to wear depending on where you're going and my little sister kept insisting she wanted to wear healed sandles.

My mum kept explaining to her until she eventually lost her temper with my sister and told her off.

My little sister looked over to me then back to mum and exclaimed 'well you can just sex off because i don't want to go out with you!'

I don't think i've ever laughed so hard in my life.