I don’t understand nor do I know what a Rihanna is
You are focusing on the wrong part of the Twitter Employee’s sentence.
You’re not missing a thing. Think garbage, trash, crap, filth & sewage.
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.