There are some intelligent jokes also explaining (in a very extreme way) how mathamticas works, for exameple
A mathematician and a physicist are sitting in the teachers lounge. Suddenly the furniture catches fire. The physicist is able to handle to situation. Both shocked, the physicist makes some coffee for both of them. The next day, the mathematician has the desire for some coffee and sets the furniture on fire, thus reduced the problem the previously solved one.
I often tell such a joke when it comes to a situation when either you reduce a problem to a big theorem or a previously solved one or if you want to motivate to do something directly without the use of a big machinery. Most of the students are normally stunned or look very confused, but some of them are very impressed since the know how the things work.
Is it a good thing to tell such jokes? Or are you even doing bad since this is confusing and anti-motivating ("Oh, those weird mathematicians. I don't want to get to that point!")?