Change the color theme to a garish bright orange-purple-yellow-blue. Anyone who survives through the day is a real BTCNTLK'er.
Exactly... some kind of real gawdy and difficult to tolerate layout as if it were "art".... Proven usage would be making a certain number of posts on that day, such as 5 or more, to thereby be labelled as an "April addict" for the remainder of the month. I would expect to receive such label, unless I happen to be non-forum busy on that day.. for some random and unlikely reason.
Edit: After browsing through the remainder of this thread (so in my mind, I am sufficiently caught up), I thought that some of the proposed April fools changes would be very difficult to achieve beyond just making an announcement, and then if there is a kind of reversal issue, some people could become disgruntled by the joke.... In other words, it is going to be difficult to beat the 2018 april fools joke... that was a real good one (and seemingly easy to reverse).
For an additional possible joke suggestion, I had thought that something like disabling all hat avatars would be great, but I just don't know if there is an easy enough algorithm to filter the type of avatars, and another problem would be to reverse the joke.. might not be easy, either. Anyhow, the ban of hat avatars premise could be that a kind of cult has established around hats, and such cult behavior takes away from forum cohesion.

Incumbent users of hats would be disallowed from employing the use of any kind of avatar for one year.