Pretzel Sunday is observed on 4th Sunday before Easter in Luxembourg, where it’s called “Bretzelsonndeg.”
A boy can offer a pretzel to a girl he fancies. If she accepts, the boy can visit her house on Easter, and expect to be given some eggs.
In leap years, it is the girl offering the pretzel, and the boy offering the eggs in return later at Easter.
The 4th Sunday before Easter is also referred to as “the third Sunday of Lent.”
The custom has now largely been replaced by Valentine’s Day a month earlier.
It’s perhaps easy to see why special days with fixed dates, such as Valentine’s Day, gain in popularity over those with shifting dates and complex calculations, especially when the base for the calculations is less relevant to people than it was at one point.
There is also now a “Pretzel Day” celebrated in April on a fixed date.