An all-time hall-of-fame NSFW spam event occurred this week: a hacker broke into a school messaging app to send a picture of a guy’s gaping asshole to the parents of young school children across the country.

The episode involved a popular school messaging app, Seesaw, that helps elementary schools communicate with parents and students. Used by districts throughout the U.S., Seesaw’s tag line is: “Elevate Learning in Elementary.” The company’s website says that it has a monthly user base of more than 10 million teachers, students, and family members.

Typically, the app is used by teachers and administrators to share lesson plans, school updates, and other important info. But on Tuesday, parents nationwide began receiving messages featuring something fairly unusual: an image of a man bending over and spreading his butt cheeks and asshole wide open. NBC originally reported the incident, and Motherboard later revealed the nature of the image that was shared widely via the app. It is believed that the image may have been shared with parents in states as far flung as Colorado, Illinois, Pennsylvania, Michigan, Minnesota, Kansas, South Dakota, and New York.

Seesaw has put out a significant amount out information about the incident. On Wednesday, it issued a short statement confirming that it had been hacked. “It was brought to our attention that a link to an inappropriate image was being shared via the Seesaw Messages feature. It appears that specific accounts were compromised by an outside actor,” the company tweeted Wednesday. Seesaw said that the company itself was not hacked but that individual user accounts (presumably belonging to teachers or administrators, given how many recipients there were) were compromised via a coordinated credential stuffing attack. Seesaw said that “widely available compromised emails/passwords that were reused across services” were employed by the hackers to log in to specific accounts and send the explicit pic.

It’s not exactly clear who is responsible for all this madness, but one thing is for sure: Seesaw’s Twitter account has been awash with complaints from what appeared to be angry parents. “This was horrendous and I hope you can let all users know how it happened and what measures have been taken to prevent it happening again,” said one user.

“How will you help to clear the name of the innocent people whose integrity was tarnished by this?” another hilariously asked.

Yet another user summed things up nicely: “Butthole pics being sent out via seesaw. Don’t open unless you want to see an asshole up close.”

The trend of cybercriminals hacking schools to share NSFW material is well established. Hackers will commonly infiltrate school district Zoom meetings or websites to share porn and other offensive material.

In this particular case, Motherboard reports that the image shared with parents appears to have been the infamous “Goatse” meme. Don’t know what that is? Here’s a quick refresher.

Goatse is an old “shock site” that originally launched back in 1999; the site just said “hello” and featured an image of an asshole being spread open. Shock sites, which typically feature a single gross-out image or video, were pretty popular back in the mid-2000s (see “Meatspin,” for another example). At some point, Goatse became a meme and was shared widely throughout the internet. The developers behind the original site also eventually tried to turn the image into a cryptocurrency token. In 2017, the website began advertising the launch of a “Goatse Coin,” though it’s unclear whether that token ever actually materialized. The website has flirted with other Web3 endeavors over the years and appears to have launched an NFT collection at some point.

It’s unclear just how many people were spammed with the notorious butthole image, so we reached out to Seesaw to try to get more information on the incident. We will update this story if they respond.