Tsjûke en March is an etiological saga from Friesland and explains the origin of the name of the Tjeukemeer (Tsjûkemar).
A first version:
Two farmers' wives were returning from milking when they discovered a fire. One farmer's wife carried the milk and the other carried nothing. The latter said that the milk should be used to extinguish the fire, but the former wanted nothing to do with that. Reason enough for the farmer's wife without milk to call her companion Tsjûke and therefore a bitch, because Tsjûke meant a dog. The word remained linked to the region. And that is how Tsjûkemar would have gotten its name
A second version:
Once upon a time there were two sisters, Tsjûke and March. They were together when a fire broke out. However, due to the dense smoke, they lost sight of each other. They tried to find each other by calling each other's names. Their voices could be heard in the area for a long time, anyone who listened carefully could understand Tsjûke, March, Tsjûke, March, Tsjûke, March...... And that is how Tsjûkemar got its name.
Source Wikipedia