in the trouser department
1. Literally, relating to or having to do with trousers or pants. Of course, in the trouser department, a nicely fitted pair of slacks will always look more respectable than tracksuit bottoms.
2. slang Relating to or concerning a man's penis or its physical aspects. Look at that guy in his big flashy sports car. I reckon it's compensation for not having much in the trouser department, eh?