Mine had a meltdown once when shopping, sat down on the floor and shouted "I am NOT going into Marks and Spensives" again - of course it has been called that ever since!
Another time we were in JL and a very dark skinned lady at the till was wearing a very lurid green eye shadow, DD shouts (and she still does! Has no library voice!) "Mummy, why has that lady got her face painted?"
The young son of a friend of mine was taken to his first football match by his Dad, and of course heard some colourful language for the duration of the match. Roll on a few months and fortunately he hadn't repeated any of it until one day whilst in the local cafe he asked to go to the loo - so his Mum said fine you go (you could see the door etc from the table), you'll be fine, don't forget to wash your hands etc .... so off he trotted, only to open the door shortly afterwards shouting "Mummy, there's no fucking toilet paper!" Ground swallows Mummy up!