An engineer hears that a famous mathematician will be giving a public lecture, and always having a soft spot for math, he attends. The mathematician then talks at length about all sorts of amazing phenomena that happen in 17 dimensional space. The engineer, amazed at this mathematician's intuition for 17 dimensional space, goes up to him afterwards and asks 'How do you picture 17 dimensions?", to which the mathematician answers 'Oh, its easy. Just imagine n-dimensional space, and set n equal to 17.'
My dad (an engineer) loves that joke.