Ahead of I/O, Google sent out swag to attendees who won tickets for last year’s canceled developer conference. The box includes a Google I/O 2021 sweatshirt that happens to include an Easter egg to a mystery date/time tomorrow.

The gray Google sweatshirt for 2021 features a blue I/O logo on the chest and left sleeve. Upon closer inspection, you’ll notice that there’s a string of characters to the left and right of that latter logo. It’s barely visible and you have a better chance of feeling something is there rather than seeing it. 

(1621378800 && G) ? I/O : □;

Only a few people have noticed that there is a sequence on the sleeve, with @ytakio3 on Twitter realizing that the numbers can be converted to UNIX Epoch time, or Tuesday, May 18, 2021, at 23:00:00 GMT. 

My colleague Kyle Bradshaw takes the parentheses to mean that we should take that statement aside and evaluate it, leading to one of two results per the ternary operator:

“If it’s past this time, and G is true”

In the case that it is true (the “?”), then “I/O”

Otherwise (the “:”), then “□”

It’s unclear what is happening at 4 p.m. PT tomorrow. In terms of the I/O schedule, there’s an AMA on Progressive Web Applications and (Project) Fugu, while there are four Meetups for the Americas: Latin@s en Google I/O, Dev Library Meetup, Server-side Kotlin developers, and Women in Voice Meetup. None of them quite match up with this puzzle.

Another possibility is that something is happening in I/O Adventure. Google has already scheduled events like a group photo for Android developers in the week, and there could be some sort of fun activity at the marked time. There’s usually a concert on Wednesday evening at I/O, and this could possibly be the substitute.

Dylan Roussel contributed to this article.

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Kyle Bradshaw contributed to this article

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Abner Li

Editor-in-chief. Interested in the minutiae of Google and Alphabet. Tips/talk: abner@9to5g.com