I've mentioned the phallic root model before. It brings out giggles every semester when it makes its appearance, and last week's lab was no exception.
One of my students asked me to come show her the difference between a couple of things she was supposed to be able to identify through a microscope. While I was trying to find the various things to show to her and giving her explanations, I heard the group of students behind me giggling.
I turned around, and saw them holding the root model and thought nothing more of it.
This picture was just emailed to me, and now I know what the giggling was really all about.