The author believes that issues of behaviour in the mathematics classroom are intimately connected to views of mathematics and the learning of mathematics. Maths teachers' perspectives on classroom behaviour will be influenced by many factors, but one often neglected and highly significant factor will be their view of mathematics as a subject. In this article, the author suggests that important mathematical ways of working are sometimes labelled as "bad behaviour". Teachers should be actively working to make space for these behaviours to grow in the mathematics classroom, however inconvenient they might be at times. Pupils should be allowed and encouraged to "misbehave" mathematically in ways that extend their mathematics. The author does not think teachers can do it through lists of unbending "classroom rules" or simplistic notions of "time on task". He thinks that the teacher's attitude and example to questioning the obvious and engaging with surprises is crucial.