Sandwhale originates from the manga GTO (great teacher Onizuka). There is a character who uses Sandster as a nick.
It could also originate from my hatred toward lakes, seas or any large water areas. Well I don't really hate them, I hate being in them. I like boating but can't stand being in water. So I'm just a whale in the sand who loves those long showers but who doesn't really want to go and swim.