I always like joining in the secret finding discord stuff. BfA had some cool ones! Baa’l, Waist of Time, Hivemind. Bunch of other hidden easter eggs and rewards too. It’s lots of fun working on those with everyone and I usually spend the first week or two of the expansion doing nothing but roaming around searching for those things.
I also spent an obsessive amount of time in Stormsong convinced the bee mount was actually in game secretly. I found “clues” that I put together as a story/puzzle of what it could be. Which turned out was only my own madness. 
But yeah, good times.