A true story, when I was about 4 I apparently asked my Dad what holding two fingers up meant. My old fella who looked after us whilst my mum was working evenings said it was a rude word, he wouldn't tell me but I wouldn't stop asking him. Eventually he said, "ok I'll tell you but you mustn't ever say the phrase" explaining it meant "fuck off" stopped my incessant questioning.
So later in the evening my mum arrived home from work, my dad said "it's time for bed son, I replied "fuck off, I'm not tired".
My dad said in later years him and my mum couldn't contain their laughter as I was sent to bed.
Ironic thing was my mum passed 5 years ago and I never once swore in her company and I never heard her swear until the night she died. She was in Hospital and an overweight auxiliary nurse passed her bed, she said "there's some right fat buggers that work here"!