It isn’t hard to understand at all. Not sure why you can’t understand the words NUKED and FALLOUT SHELTER if English is your first language.
The TWITTER employee is promoting this propaganda..albeit in the disguise of a joke.
Can’t be bothered with this twitter nonsense and YES, English IS my first language...has been for almost 3/4 of a century. So, since you had to get snarky, to you I say
Mettilo dove il sole non splende