I have two contributions to this node.
The first is a memory I have of health class in grade 7. We were learning about the human body. At one point, the teacher (also our gym teacher!) asked us to name different types of cells we'd heard of. Of course, some keeners raised their hands to mention "muscle cells", "nerve cells", "blood cells" etc. Then one guy said "penis cells". The gym teacher looked somewhat confused for a moment and then said "Uh, I guess those would be muscle cells". Of course everyone thought this was funny, but the man was obviously woefully underprepared (as became more obvious later). Fortunately, my parents had given me a couple of very progressive books on the subject, so I didn't have to rely on his expertise.
The second is a photo tacked to the wall in an office in my department. It is of two Kenyan (I think) Boy Scouts, maybe 13-15 years old. They are, according to the caption, carving wooden penises for use in rural sex education condom demos. Holy cow, I have never seen a) bigger grins on human beings, or b) bigger wooden penises, in my life! I mean, wow, these things were about a foot long! I guess they were having fun, and serving a worthy cause at the same time...