Trump became the first sitting president to attend a Supreme Court hearing, but it didn’t seem like the majority of justices bought the administration’s argument that the 14th Amendment doesn’t actually guarantee citizenship to all people born in the U.S. regardless of their parents’ national origin ― even though that’s been the interpretation for more than 100 years.

And he may not attending any more hearings, based on his angry reaction to Wednesday’s session that he posted on his Truth Social platform shortly after storming out.

“We are the only Country in the World STUPID enough to allow ‘Birthright’ Citizenship!” he wrote.

Donald Trump reacts to Supreme Court hearing on birthright citizenship.

TruthSocial/@realDonaldTrump

The post was full of classic Trump trademarks, including arbitrary capitalization and, yes, falsehoods ― the easily fact-checked kind.

In addition, there are at least 50 other countries that have birthright citizenship, albeit in a more limited form.

Trump’s claim that the U.S. is the only country “STUPID enough” to allow birthright citizenship was probably just an angry reaction to the way many of the justices on the court responded to Solicitor General D. John Sauer’s attempts to argue for its cancellation.

For instance, Trump appointee Neil Gorsuch seemed to catch Sauer a little flat-footed when he asked if, based on his argument, Native Americans born today would qualify for birthright citizenship.

Sauer’s response: “Uhh, I think so?”

Justice Amy Coney Barrett ― also a Trump appointee ― warned that the potential effects of removing birthright citizenship could be “messy on some applications.”