I have one which may not be in there - it's hot off the lips of some six year olds I know. Actually, a couple of months back co-parent said she heard a radio discussion of new slang which mentioned this and the very next day we heard Olle say it: "I'm going to verse you". It means "I'm going to play against/compete against you". It stems from the word "versus". (A misunderstanding of "versus", it could be argued.) He'll also say "I'm versing you". I heard another boy say it during the holidays too.
Then there was the time he ran onto the beach, saw something interesting and called to his friend to come and look - "Hey, this is sick!" I know that's old hat as far as slang goes, but it still gives me a little shock to hear it.