The 'F' Bomb

I picked Rich up from school today and we were driving along and he started to sound out and list words that began with 'F' he got up to about the 4th word then goes "fff fff fff F#ck" I'm like "RICHARD!" he was so cute, he first reaction was "oh, oh.  Sorry! I was just sounding out F words" Lol.  I then explained that was a bad word.  

He may have heard us say it on rear occasion but it was in a song on the radio this morning, I quickly changed the station but the damage may have been done...  Oops!!