It's hard to give a favorite Pink Floyd song!
Right now, I'll say Wish You Were Here, but I also love Hey You, Nobody Home, High Hopes, Us and Them, Learning to Fly...etc
John Lennon
Cheech and Chong because they are original.
Ben and Owen don't strike me as an awesome onscreen duo
How's this:
Jack Lemmon and Walter Matthau
or
Richard Pryor and Gene Wilder
That's actually the only song I know for them, and yes I know it's a cover, but it's way better than Lionel Richie's version :)
Limelight
Genesis (Phil Collins era)