* The song parodies relating to TV shows where he actually incorporates the lyrics of one song over the instrumentals of another song - ex: "The Brady Bunch" lyrics over "The Safety Dance", "The Beverly Hillbillies" over "Money For Nothing", a verse of "Gilligan's Island" in "Amish Paradise".
* For that matter, "Bohemian Polka". I think this is probably the closest to a legitimate cover Al has ever done.
* Any song parody where he's got someone involved in what he's making fun of in on the gag - ex: Don Pardo berating Al at the end of "I Lost On Jeopardy", Mark Knopfler himself playing the guitar on "Money For Nothing/Beverly Hillbillies".
* The songs he does where he's satirizing a certain song STYLE rather than any specific song - ex: "Trigger Happy" ('60s surfin' tunes) and "Those Were The Good Old Days" ('70s soft-pop ballads).
* The song parodies where his target is some hugely-hyped movie; these are unique to the rest of his song parodies because in every case, instead of using a more recent hit song for the instrumental as he does with his other spoofs, he goes back to classic pop/rock hits instead - ex: "Yoda" based on "Lola", "Jurassic Park" based on "MacArthur Park", "The Saga Begins" based on "American Pie", "Ode To A Superhero" based on "Piano Man".
Since most of his other songs hit on the same two subjects - TV and food - I'd like to think this narrows it down. A bit.
