According to the tradition of Weiberfastnacht, or the “Wenches Carnival,” hoards of women in the largely Catholic region descend on city halls at exactly 11:11 am to snip off men's ties to show them who's really boss.
Always on the Thursday before Ash Wednesday, the day is also known as Fat Thursday, when men generally wear old ties in anticipation of losing this symbol of their manhood, a humiliation that is also traditionally soothed with a kiss.
In Düsseldorf, the women traditionally stage the mock arrest of the city's mayor, while in Cologne the triumvirate of presiding fools, or Dreigestirn, takes hold of the keys to the city.
Thousands of costumed clownish revellers known as Narren took to Cologne's streets despite extremely chilly weather. Broadcaster WDR even forecast snow showers for the day.
Besides classic clown outfits, this year's most popular outfits included characters from The Hobbit movie.
But Trier has decided to ease into Karneval this year, instituting a ban on booze in the old town until 7pm on Thursday. The city is hoping to avoid a repeat of teenage excesses last year, when 60 youths suffered injuries and alcohol poisoning.