Boy, I didn't realize I needed to set the explicit "irony flag" on that post! The idea is that my math teacher was making a math joke, stimulating his students' curiosity to think about deep things like "what does it mean to add and how do you prove things that seem intuitive" and informing the class that people have written serious and long books on the foundations of mathematics. None of my kids' math teachers (so far) have made any math jokes...