Mayhap i'm just to darn old, but I fail to see anything interesting, useful or humorous. As a relationship diagram, it looks rather straighforward and somewhat simplistic. Aa an example of a relationship diagram, for "illustration" or teaching purposes. it doesn't show the range of relationship types and doesn't -at first glance- show the common errors. AS humor, I can't really read all of the table and field names, so if there is a joke buried there, I lost it.
MichaelRed