Not to rag on Sheryl Crow unnecessarily, but the category really requires mentioning that song from the early 90s called "All I Want To Do." You remember the one I'm talking about - Billy peels the labels off his bottles of Bud? Total slacker anthem. As is "Margueritaville," although I like that song. Sheryl Crow has another more recent song that follows the same pattern - "Soak Up The Sun." Catchy tune, slacker lyrics.
Other songs talk about leisure in a different way - as in, relief from the work day (like "It's Five O'Clock Somewhere" - which is a spin-off of "Margueritaville") - but it's the slacker-as-role that gets me. Maybe it's a function of my warped upbringing, but I just can't imagine a life in which I didn't have to do anything I didn't want to do.