The Online Dictionary of Playground Slang. A lot of the entries don’t seem particularly “playground,” and the definitions can be haphazard, but the brio and Chris Lewis’s commentary make up for a lot. Examples:
man-of-atlantis: Useless swimming stroke based on Patrick Duffy in the television series.
manners: ‘Manners’ was a term used to point out that another kid was inferior to you, in the way they dressed, at sports, physically, or just in general. If you were ‘under manners’ this could also mean that you were in trouble, or being watched by a teacher in class, so had to be quiet. Obviously, it was used to tease and show that you could still continue to behave badly, whilst they were – indeed – ‘under manners’, I heard this all through secondary school. Incidentally, my school – Quintin Kynaston – was the school that Graham McPherson, ‘Suggs’ from Madness went to, and wrote the song ‘Baggy Trousers’ about!