The Shag Dance is sort of a lazy jitterbug, done on beaches at night, always with someone of the opposite sex. Therefore, the music shaggers picked for their soundtrack had to be sunny, sexy, fun, and lazy. Depending on who you talk to, shagging can be done to songs as diverse as Elvis' "Return To Sender" and Marvin Gaye's "Sexual Healing," but the general consensus is that there should be a slow shuffle at the bottom and some sort of southern soul on top.
The big hits of shag are almost all one-hit wonders, cherry-picked for their utility - Willie Tee's "Teasin' You," the O-Kaysions' "Girl Watcher" - but that also gives the scene room to breathe. And, as has been proven by its continuing popularity, room to expand.
My favorite Shag Dance song!