I looked it up
I found some pictures referencing Feb 12, 2024
But different places in Western Germany:
Cologne, Duesseldorf, Mainz, Bonn, etc
Apparently the holiday is Rosenmontag, Frolicking Monday, throughout the Rhineland (all these cities are on the Rhine River)
So it's an analog to our Mardi Gras (French for Fat Tuesday) in New Orleans: a time for debauchery right before a time of penance, Ash Wednesday and the season of Lent