Dog Residue

You receive Dog Residue from using the Annoying Dog in your inventory after getting into the piano room in Waterfall.

Uses
Using the Dog Residue fills up your inventory with Dog Residue and occasionally a Dog Salad, a free healing item. Dog Residue can be sold to Temmie in the Temmie Shop for 1-4 gold, and Dog Salads for 8 gold. Keeping one Dog Residue at all times ensures a farmable source of gold, if a bit tedious.