In German this literally translates to something like “cute sand man”. Because in German you can just add an " I" at the end of any noun to make it sound cute and small. So “Sandi” can be thought of as a kind of diminutive of the noun “Sand”, similar to “Bauchi” from “Bauch” which is stomach. The correct dimunitve of “Bauch” would be “Bäuchlein” but this refers more to the perceived size of the object.
In German this literally translates to something like “cute sand man”. Because in German you can just add an " I" at the end of any noun to make it sound cute and small. So “Sandi” can be thought of as a kind of diminutive of the noun “Sand”, similar to “Bauchi” from “Bauch” which is stomach. The correct dimunitve of “Bauch” would be “Bäuchlein” but this refers more to the perceived size of the object.