Nephew of a friend of mine, 5 years old, struggling with the Latin in Harry Potter...
Runs up to people and shouts "Smelly armpits!"
Well, it's easier to say than Expeliarmus!
I'm constantly amazed at Nephew Oli's ability to say the names of dinosaurs. Of course, he only hears them spoken in documentaries (being 4, his reading is still limited, if at all) so he can parrot perfectly. I see them written down, and have to do them a syllable at a time, and might still get the emphasis wrong.
Carcharodontosaurus is one where he beats me hands down.
I got firmly told off by one of the Cub's teachers over dinosaurs
One of the younger cubs was into Jurassic Park, and asked what DNA was. Parent knew I was a medic, so I was asked
Now explaining DNA and RNA in simple terms is easy enough, and wrote down the full words.
Following week, parent came back, that teacher was unimpressed and that being able to understand and spell DNA and RNA was not suitable for an eight year old
Oli went to a museum with his Dad, pointed at a vaguely shaped fossil, and said "That's Pachycelpalahasurus", and wandered off. Dad was left wondering how the heck he knew, and could only assume that he'd 'read' the label - IE, recognised the shape of the word, as opposed to actually spelling it out, because he's still struggling a bit with 'cat'.
While I was there, he was playing a game on his Mum's Itouch. A caption came up, the name of a dinosaur, and 4 pictures, and you had to touch the right one. I was watching, and reading out the dinosaur names to him - he got each one spot on first time. But then he said "Stop helping me, it's cheating!". I stopped reading, and he started to touch pictures at random each time until he got the green tick. Bless him, he thought knowing which one you were looking for was cheating, and that he was supposed to guess at random. He still enjoyed it, but not quite how it was intended.