Mentioned in Pyramids, this is a more-than-usually obvious reference to a Roundworld phenomonon: the Scarab Beetle of Ancient Egypt was a potent and ubiquitous symbol. Khepri the Scarab even pushed the sun across the heavens, just as Scrab does over the skies of Djelibeybi.
In The Last Hero, there is a double-page illustration of the Gods gathered around the gaming table in Dunmanifestin. An interesting background detail is a small sun, being pushed by an attendant dung-beetle - most probably Scrab. In The Last Hero, the marginal notes of manuscripts penned by Leonard of Quirm re an interesting read. Leonard speculates that the minor planets of the Discworld system are nothing more than balls of dung, gathered from the four world-elephants by cosmic dung beetles, and that close astronomical observation of these was the inspiration that called Scrab into being as a god of Djelibeybi. And once faith in a scarab-god was established, it gave him a mandible-hold in Dunmanifestin.