Would you use a joke to initiate a class discussion or topic?

As a physical chemist who was a research spectroscopist, I enjoyed the meme above.  However, would you use humor like this (or in any other form) to begin a class?  Here's what I mean.  Imagine you walk in to a physical science, biology, chemistry or physics class and your teacher displays the meme from above using the projector.  Some students giggle, some don't get it, some aren't paying attention, and some are too cool to respond.  I personally think a little humor (especially if it is not offensive) will make the lesson, whatever that less is, be more memorable.  At the very least, students are jarred away from whatever was on their minds as they travelled to your classroom.  That, in itself, should make them better learners.

Give it a try.  I certainly will (and do).  I promise that the next time I teach light to students, this will be the first thing they see.  By the end of the class, I'll show it again and see if they laugh a little more.