How would they know there is a third box, much less what its label says?
Sometimes being the omnipotent narrator has its advantages. 
Maybe the second box has a window in one of the other sides and the label is displayed through that?
Maybe one of the New Year’s celebrants is Homelander and the second box isn’t made of zinc?
But “omniscient narrator” is definitely the “horses, not zebras” answer.
Obviously the openers of the first box were resourceful enough to hop onto a plane and fly into a different time zone where it was still 2024. And the creator of the time capsule anticipated that possibility, and so included the third box so they’d still be stuck.
If they are on Polynesian Samoa, they can open it and then imediately take a plane and cross the dateline to US Samoa.
Open the second box. They can’t open the third box (unless they cheat) but they can know whats written on the side.
And here I was expecting Michigan J. Frog to hop out and immediately start a rendition of “Michigan Rag”…
Either that, or a cat that may or may not be dead.
Or, per LeGuin, may turn out to no longer be in the box at all.
I suppose it might contain a simple picture of a box. With the caption “Ceci n’est pas une boîte”.
Break the damn third box open and to Hell with whoever set it up. I don’t care if the box was the containment vessel for a basilisk, a xenomorph facehugger, an open sample of Captain Trips, or a large charge of antimatter.
This is why we can’t have nice things.
If we’re lucky it’s just a box of Cap’n Crunch from year [whatever]. Which probably hasn’t gotten stale yet; that stuff is eternal.
“The most important quantity for meteorologists is of course the product of latent pressure and temperostrophic enthalpy, though ‘how nice the weather is’ is a close second.”
This one’s too esoteric for me. I mean, I’ve seen diagrams that are vaguely similar to that in various thermodynamic contexts, but without knowing what one of the real ones is supposed to mean, I can’t interpret how this fake one is humorously different.
Here’s some (scant) info on a real one with an example.
Meteorology is one of the most baffling sorts of messy applied science I’ve dealt with. These diagrams are real info-dense with the plotted data speaking volumes to the experts and being a “blah blah Ginger” experience for the likes of me. Despite my knowing the basics.
As usual, Tom Weller’s “Science Made Stupid” showed the way:
“You may notice the first half of these instructions are similar to the instructions for a working nuclear fusion device. After the first few dozen steps, be sure to press down firmly and fold quickly to overcome fusion pressure.”
Mythbusters managed to do it 11 times, with a sheet of paper the size of a football field. Would be more interesting to see how big the paper would need to be to fold it 189 times…
You know that the length/width [more than] doubles each time you fold it?
There was that girl who, for extra credit in mathematics, folded a 10x10cm square of gold foil 12 times, as well as folded a 1.2 km-long roll of toilet paper 12 times, so I’m not sure why Mythbusters was not ashamed to broadcast their inferior performance.
Britney Gallivan
Since 2189 is a bit more than 7x1056 thicknesses, I’d guess a pretty big piece of paper. Even if it was a sheet of nucleons, it wouldn’t fit in the observable universe.