The Twelve Networking Truths
RFC 1925 (The Twelve Networking Truths) is a short yet interesting reading. I believe it applies to Software Engineering in general and not only to Networking in particular.
Rule #3 is probably the most instructive:
[Edit Dec 5th: Updated link]
With sufficient thrust, pigs fly just fine. However, this is not necessarily a good idea. It is hard to be sure where they are going to land, and it could be dangerous sitting under them as they fly overhead.