He's a detective who OCD and a serious germaphobe, and when three homeless guys try to hire him to figure out who killed their friend, he wants nothing to do with the case. One of his objections when his assistant insists he take the case is that hobos "make their own gravy" - just what that means is meant to be horrifyingly funny. Which is given a callback later in the show when they arrive to share Thanksgiving dinner with the main characters and they have, in fact, brought their own gravy.

So that's what I remind my kids of whenever we talk about the homeless. That they "make their own gravy". My stepdaughters are younger, and suitably squicked out.