When a property starts out insanely popular, but then the general consensus is that it's not popular or not cool, and then later it's insanely popular again and (usually) stays that way
"I used to really like Five Nights at Freddy's, then I hated it, now I like it again" -Luna
"Ah yes, the old Minecraft effect" -Christine
When you take a second to grab your bong, rolling paper or pipe, so 4:20 passed, but now it's 4:20 two: electric boogaloo
Jay: "Shit man, you took too long finding your stuff, it's 4:22 now"
Bob: "Don't worry, that means it's 4:20 two"