Premise: Today Wikipedia, the free encyclopedia that anyone with access to the Internet can edit, was the victim of an onslaught of practical jokes, as April Fool's Day kicked in various timezones around the world, at least those parts which follow the Gregorian calendar. It is believed that Wikipedia contributors were kept busy tidying up and removing prank articles and changes made by other Wikipedia contributors, and were expecting to be cleaning up the aftermath for days afterwards.
Hypothesis: Wikipedia is not free.