You may think this is a metaphor, and it very well could be, but the reference here is purely literal.
The kitchen sink is from 1961, with a mechanism for stopping it up to retain water for dish washing. Aged Parent felt that somehow, no one could really be sure, the water was surreptitiously draining, so she made sure the seal was perfectly watertight by (I kid you not) cleaning the edges of it with her fingernail (as reported in detail to me). She made certain of the hermetic seal, showed me the now-operational sink, and justified this entire project with: "...otherwise we would be wasting Joy." Yup, the detergent.
See why I am in an existential crisis?
