Going to Wikipedia to look up a simple piece of information, and ending up spending several hours reading about things you didn't know existed.
Last night I went to Wikipedia to look up the history of the $2 bill, and ended up in a wiki-hole for 3 hours.
The infinite regress of looking something up on Wikipedia - similar to a philosophical "rabbit hole", a wiki-hole is when you cannot be satisfied with a single article and find that there is always at least one other article that must be read... ad infinitum.
I meant to just take a minute to look up Superman on Wikipedia, but was caught in a wiki-hole for hours.
"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!