Supernatural has been trending on and off since March 5. At first glance it doesn't appear like anything major happened, which had people a bit baffled, including yours truly.
It looks like there's been a surge in general spn posting (there's been quite a lot of art appearing as well), with potential organised effort into tempting the universe. What's more, an additional timestamp was published for Ninety One Whiskey by komodobits, a very well-known destiel fanfic from 2016, which had been posted as a commission for Rally for Palestine [x] [x], and which got people posting as well. Not to mention that the confusion about the trend likely caused people to post even more about Supernatural, trying to find out what kind of disaster had happened this time, which would've contributed to the tag appearing.
Or maybe it's just yet another time when Supernatural trends just to disturb the peace and remind people of its existence. Wouldn't be the first time.
Big shoutout to @goldrushzukka, @destieldisaster, and @casismybestfriend for the information, this one had me confused [x].
It's been three years so I'm willing to admit it was kind of delusional of us to think Samantha Ferris and Chad Lindberg were going to throw a Destiel wedding on twitter