Literal translation
it matters to me as much as my first pair of shoes
Meaning
I couldn't care less
Explanation
This phrase conveys a complete, almost amused indifference toward something. It rests on the rare verb enchaure, meaning to matter or to be of importance, which nowadays survives mostly in negative or fixed constructions of this kind: not enchau amounts to saying the thing counts for absolutely nothing. The comparison picks a child's first pair of shoes, an object nobody gives a second thought to once grown up, forgotten at the back of a cupboard or thrown out long ago: their fate today concerns strictly no one. The pairing produces a comic effect through the almost absurd precision of the chosen detail, where a more general comparison might be expected. The register is familiar, used to cut short a worry or a reproach considered baseless. Since the verb form enchau has fallen out of everyday use, the expression carries as much linguistic curiosity as conversational value, and survives chiefly among speakers who have kept the old people's way of speaking.