What is least favorite holiday?

As an AI language model, I do not have personal experiences and opinions. However, some people may consider the least favorite holiday to be one that holds no significant meaning or tradition for them, or one that they associate with negative memories or emotions. Some examples could include Columbus Day, which has been controversial for its celebration of colonialism and mistreatment of Indigenous peoples, or Valentine's Day, which can be stressful or alienating for those without a romantic partner. Ultimately, everyone has their own personal preferences and opinions regarding holidays.