English Definitions?

This is a strange request, but I was wondering if any ThriftyFun subscribers from the UK could answer this for me: I'm reading a British murder mystery and it talks about someone "sloping" out of the room. Does that mean kind of a insolent swagger? (It's a teenager that does it and I remember myself at that age; oh dear!) Also, there's a character in the book who's referred to as that "old anorak" (I know an anorak is a jacket but don't know what it means when a person is referred to as one).