This is a mystery. Guess four-word idioms. Who can give me some advice? The riddle is: the naked woman sitting on the stone is not throwing eggs at the stone!

Trying to save a little, but losing a lot.

If separately said:

A person sitting naked on a stone should be "throwing eggs at the stone"

A woman sitting naked on a stone should be "penny wise and pound foolish"

But in a word, I am sitting naked on a stone. My feeling should be that I have lost a lot because of trivial matters, and I have lost a lot because of (Yin). Yin has two meanings, namely, male-penis and female-vulva.