Time to Pee! is a children's picture book by Mo Willems. Released in 2003 by Hyperion Books, it is a book about toilet training. It also contains a progress chart and a page of motivational stickers. The book's instructions are presented by a group of mice toting signs and banners. Willems joked in an interview, "My basic theory is that kids will never listen to adults, but they will listen to an infestation of mice."