"Going down a wikihole" is a term used to describe the phenomenon in which one opens a wiki article about something cool, clicks on a link to another article about something ever cooler, and eventually comes up for air 6 hours or so later after having clicked on all manner of related cool wiki links. The word is based on "wiki" as in "wikipedia" plus "hole" as in rabbit hole, and is inspired by the notion that wikipedia offers its own highly seductive type of single-user rabbit hole. It is similar in meaning to "wikitrail" but implies a certain loss of control at some point.
Damn! It's already 2 a.m.! I just wanted to look up this one thing about coffee and ended up winding my way through a four-hour wikihole!