The Anti-Defamation League has a database of official hate symbols. It's called Hate on Display, and it includes the Aryan fist, the burning cross, the swastika and the (((echoes))) symbol. The ADL added Pepe the Frog, a once-innocuous 4chan meme, to that list Tuesday afternoon.

"Once again, racists and haters have taken a popular Internet meme and twisted it for their own purposes of spreading bigotry and harassing users," ADL CEO Jonathan A. Greenblatt wrote in a statement sent to Mic. "These anti-Semites have no shame. They are abusing the image of a cartoon character, one that might at first seem appealing, to harass and spread hatred on social media."

When did this frog cartoon become racist? Pepe started out as a meme popular among the discord-loving trolls of 4chan, a site once described as the "dark heart of the internet." This is the forum that gave birth to Anonymous, LOLcats, Rickrolling and various bombing hoaxes.

But with the rise of online trolling, 4chan culture and the conservative alt-right movement bled into the mainstream, and so too did Pepe. Soon, everyone was using various permutations of the ugly green frog as a reaction meme. Even Katy Perry.

Then the dark heart of the internet reclaimed the frog. On forums like 4chan, 8chan and /r/The_Donald, Pepe became a virulent racist, sometimes wearing a Nazi uniform or the white robes of the Ku Klux Klan. Other times, he was stylized as a Jewish caricature with yarmulke and payos.

This summer, Pepe became a common avatar for white supremacy, "race realism" and national socialism on the Internet.

In June, after Mic exposed the use of echoes, or triple parentheses, as a way for white supremacists to covertly identify Jews on social media, the ADL added it to that same list.

Can a meme really be racist? Yes and no. "The mere fact of posting a Pepe meme does not mean that someone is racist or white supremacist," the ADL explains. "However, if the meme itself is racist or anti-Semitic in nature, or if it appears in a context containing bigoted or offensive language or symbols, then it may have been used for hateful purposes."