what it is: unfavorable semicircle
where i found it: atlas obscura
One of the most perplexing internet phenomena to date is the youtube channel known as Unfavorable Semicircle. No one can pin down if it's a secret code being broadcast, the workings of a total madman, or an alien transmission. It's way too expansive to be any kind of dada inspired joke. As it's been getting more attention, I'm not sure how much longer it will last. As of this writing, they last posted two hours ago. Here's a good article from Atlas Obscura that does into more detail.
Here's the channel itself: UNFAVORABLE SEMICIRCLE