1. Find a Wikipedia entry on some important real-world subject that a normal human being seeking useful knowledge from an encyclopedia might look up.
2. Then, try to find a similar or related entry about something completely useless to 99% of the population that describes in great detail something that no one could possibly need to know. The key to making a good matching pair is that the second, completely useless entry should be much, much longer.
A few examples from the article:
Civil War (comic)
List of fictional gynoids and female cyborgs
One from calamityjon:
Some from the boys on the High Hat forums:
'Body and Soul'
And a few of my own:
Star Trek novelizations
Sgt. Alvin York
G.I. Joe: A Real American Hero
Three Rules of Robotics
And you know what this means, don't you? It's your turn! Hit me with some of your favorite Wikigroans. BONUS: if you misunderstand the whole concept, I will make fun of you! Now GO!