Booker T. & the MG's: Green Onions
Because it has placed prominently in soundtracks from American Graffiti to Quadrophenia to Get Shorty to The Sandlot, and because it gets played at ballparks and on commercials a bunch, most people recognize this funky 1962 soul instrumental immediately when they hear it.
But in my experience, hardly anyone (except perhaps our own beloved LD) knows the song by name, or knows that it was the house band for Stax records -- yes, those guys playing behind Sam & Dave, Wilson Pickett, The Staple Singers, and a holy host of other Stax superstars -- who first recorded it and made it famous.
Perhaps folding it into this theme will help you find it when you need it. Because when it's time to get down to it, we all need to know where it's at.