Literal translation
he laughs when he burns himself
Meaning
he or she never laughs
Explanation
This expression means that a person almost never laughs, and it works through an ironic contrast between the situation described and the real meaning intended. Literally, it describes someone who would only laugh from the pain of a burn, which amounts to saying that laughter is as rare for that person as pain deliberately sought out, in other words that they never laugh at all, since no one burns themselves for pleasure. The irony lies in this absurd pairing of laughter and suffering, which by contrast underlines the usual seriousness or sternness of the person's character. The register is familiar and mocking, used to gently or more sharply tease someone little inclined to cheerfulness, with a closed face or an austere temperament. The phrase belongs to the Provençal vocabulary rich in character portraits expressed through absurdity, favouring a striking image over plain description. The verb brula, to burn, keeps here its concrete sense of physical pain, without further figurative shift.