I spotted three slang words - nob, balls and nonce. "Nonce" used to mean "sex offender" (about 20 years ago) but has lost that really. It came from "nonsense" and was used like that in prisons apparently, and spread into the outside world meaning "silly" now.

The gesture he is making is the British equivalent of giving the middle finger.

Yeah - 100%! W00t! I thought they were going to do some of the lesser-known ones though - "The Bruce-Partington Plans" anyone???