The Commission de toponymie du Québec asserts that the parish's name refers to nearby Lake Témiscouata, the sense of haha here being an archaic French word for an impasse; see Ha-ha. The Louis may refer to Louis Marquis, one of the first colonists of the region, or Louis-Antoine Proulx, vicar of Rivière-du-Loup, or perhaps the abbot Louis-Nicolas Bernier. Saint-Louis-du-Ha! Ha! is the only town in the world with two exclamation points in its name, and shares the distinction of having an exclamation point in its name with Westward Ho!, a village in Devon, in south-west England (Wikipedia)
