The speaker walks through three scars, and the tone shifts as the poem goes on. The first is a thumb scar from a pocketknife, told with a joke: the crescent moon is "drunk," and scissors "didn't make the cut." The second, from removing a skin tag, is lighter still, though it hints at a young person wanting a "perfect" ear. Even there, the speaker admits the faded mark can still be felt.
Then the third scar arrives, and the humor drops away. Someone loved was "ripped away too suddenly," leaving a hole that "didn't heal very nicely." The short, plain lines make the loss feel quiet and raw. The final fact, that scar tissue is more sensitive than normal tissue, turns the whole poem. A scar usually means something has healed, but here it means the hurt is still easy to touch.
The mood begins wry and casual, then settles into a subdued, aching honesty.