According to an unusual recent social media post, the U.S. Post Office does not want you to mail mercury.

Presumably, the tweet referred to the dangerous chemical element, not the planet in our Milky Way. In either event, the X post stated, “mailing mercury is NOT brat.”

Being “brat” does not refer to being a rude child or the Barbie Doll competitor of the early 2000s. Rather, it refers to a hit album from pop star Charli XCX. The album’s popularity and its singles, like Von Dutch and 360, have driven some to call the summer of 2024 “brat Summer.”

The “brat summer” ethos encourages embracing boldness, taking risks, and stepping out of one’s comfort zone. It celebrates being unapologetically edgy, embracing imperfections, and exuding self-confidence rather than adhering to traditional poise and conventionality.

However, like all trends, this one is finishing its course. On September 2, the day before the post office’s post, Charli XCX posted: “goodbye forever brat summer.” 

It is unclear why the Post Office tweeted this comment; a quick search of news stories on Google using the phrase “mailing mercury” does not yield many recent results.

Mailing mercury has been prohibited for years.

A 2023 reminder advisory said, “The Postal Service is reminding customers that metallic mercury and devices containing metallic mercury are always prohibited in the mail stream. This includes antique items such as thermometers, barometers, blood pressure monitors and similar devices. However, compact fluorescent lamps, which contain small amounts of mercury in vapor form, are mailable domestically but not internationally.”

The advisory also warns, “If a person knowingly mails items or materials that are dangerous or injurious to life, health, or property, they may face a civil penalty of at least $250, but not more than $100,000 per violation, the costs of any cleanup associated with each violation, and damages. They may also face criminal penalties.”

Few responders to the social media post found it rib-busting funny.

“Privatize the US postal service immediately,” one user said.

“Who is running this account a 15 yo???,” another user said.

The U.S. Consumer Product Safety Commission’s official account cracked wise and appeared to be in on a potential planetary joke. The account responded to the Post Office with, “Yeah, right like there’s an envelope big enough for that.“