rodents made them do it

Last year when there were riots on Hallowe'en, blame for the riots was cast upon women exposing themselves to the crowd in various ways, which apparently through some as-yet-unindentified physiological mechanism provokes men to break windows. This year, there were riots again, and the city has shifted the blame from girls to... gophers! In today's Wisconsin State Journal:

No one broke any windows until people at the inn incited the crowd, Verveer stressed, adding that a group singing the Minnesota Gophers fight song from a window invited trouble.