Christmas type holiday that can be thrown into any city/town.
The addition of “irrelevant” details adds local colour to a campaign world, giving the impression that the DM has thought very deeply about the history of even the smallest architectural feature.
Whistling on the sea is bad luck. It is said to mock the sound of a strong wind and will call it so nature can show the true sound. Whistling is only allowed when becalmed or when shrouded in fog.