The parade commemorates an Ypres tradition from the Middle Ages in which cats were thrown from the belfry tower of the Cloth Hall to the town square below. Symbolically reviving this practice for the parade festivities, a jester tosses plush cats from the Cloth Hall belfry down to the crowd, which awaits with outstretched arms to catch one. The throwing of the cats from the belfry is followed by a mock witch burning.
Participants in the festivities often dress as cats, witches, or townspeople from ages past.
There are various legends about how the throwing of cats originated. One possibility is that cats were connected to witchcraft, and the throwing of the cats symbolized the killing of evil spirits.
Another story suggests that the cats were brought in to the Cloth Hall (Lakenhall) to control vermin. Before modern heating and storage methods, when it got cold the wool was stored in the upper floors of the Cloth Hall. At the start of the spring warm-up after the wool had been sold the cats were tossed out of the belfry.