People
Ford was practicing being sullen and getting quite good at it.
— Douglas Adams • Life, the Universe and Everything

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
A funny observation about someone rehearsing a mood like a skill. Sulking is treated as something to practise, and the punchline is that they're improving at it. The dry understatement makes petty gloom sound like a serious craft, which is where the humour lives.
Context reviewed