Trainspotting (a now largely obsolete English hobby). Back when trains were a thing, nerds would gather at at the front end of the platform to write down the numbers of the engines. Exciting stuff. If you ever saw a movie called 'The Station Agent' with Peter Dinklage you kind of get the idea. Now a slang for a pointless, useless activity (which is where the movie about Scottish heroin addicts gets its name from).
A close second is commenting on the internet.
Where is the scar from where he was shot in that ear?