A popular acronym that means "If you know, you know". Often used as a hashtag to imply that something cool is going on and that if you don't know about it, you're most certainly not in the cool kids club.
A less popular acronym (we just made up) that means "If you want to be the first to know (after the cool kids)". Often used to get you to opt into a list where you will, indeed, be amongst the first to know...
