31 October — for many, the day conjures images of trick-or-treaters knocking on doors and other images of Halloween. However, in Wikipedia, the day is also designated a holiday — Tim Starling Day.

On 31 October of 2003, Wikipedia founder Jimbo Wales decreed the day as a holiday after Tim Starling, a developer who had recently rewritten the Wikipedia parser so that it was twice as fast. This drastically improved efficiency and speed, and a "big hullabaloo" was raised. As a result, Jimbo established the holiday in honor of Tim.

"Dude, you rock," Jimbo wrote to Tim in 2003. "I hereby decree, in my usual authoritarian and bossy manner, that today (Oct. 31) shall forever be known as Tim Starling Day. Wikipedians of the distant future will marvel at the day when the new parsing algorithm dawned upon us. Tonight at dinner, every Wikipedian should say a toast to Tim and his many inventions. In countries that celebrate Halloween, children will first say 'Trick or Treat' and then, when they get the candy, they will say 'Secure and Split' and run away, in honor of Tim's work in this area."

However, the holiday remains virtually unknown and uncelebrated among Wikipedians. There are only three other Wikipedia holidays, with one not officially decreed by Jimbo. 15 January was proclaimed as Wikipedia Day in tribute to Wikipedia's founding on that date in 2001. However, though this holiday is widely recognized, Jimbo has never officially decreed it a Wikipedia holiday. 25 January is designated as Magnus Manske Day, commemorating 25 January, 2002, when Wikipedia switched to Mediawiki software. The day is named after Magnus Manske, who helped write the original PHP script that evolved into the MediaWiki software and was also an active participant on Nupedia. Finally, 1 June was proclaimed as Brion Vibber Day in 2004 to recognize the work of Brion Vibber, Wikipedia's lead developer.