Why are they called the 'Squad'? How four freshman Democrats got their group nickname

The "Squad" refers to four minority congresswomen: Reps. Ocasio-Cortez, Omar, Tlaib, and Pressley. And it all started with a photo caption.

President Donald Trump has been on a days-long Twitter tirade about four freshman congresswomen of color called the "Squad." And while Trump's a fan of nicknames, he didn't come up with this one. Instead, the congresswomen gave it to themselves.

The nickname refers to Democratic Reps. Alexandria Ocasio-Cortez, Ilhan Omar, Ayanna Pressley, and Rashida Tlaib. It started with a November Instagram post by then-representative-elect Ocasio-Cortez – a photo of the four congresswomen seated together, captioned "Squad."

“Someone said, ‘Oh you should do a hashtag or something #squadgoals’ and then it morphed into this thing,” Pressley told CBS in an interview last week.

The 'Squad': The four congresswomen Trump told to 'go back' to other countries

It's not just 'Rocket Man': Trump has long history of nicknaming his foes

What started as a simple photo caption has grown into a broader talking point for the four congresswomen.

On Monday at the national NAACP convention in Detroit, Tlaib said that the "Squad" is "beyond just the four of us" and that "we need bold action."

"I can tell you, you are all the squad, trust me. If you support equity, you support justice, you are one of us," she said. "The Squad is all of you."

It's even an 82-year-old man from New Jersey, as it turns out.

Last week, Rep. Bill Pascrell asked to be part of the "Squad" by responding to a tweet from satirical news site The Onion, which posted an article entitled "82-Year-Old New Jersey Congressman Bill Pascrell Quietly Asks Ilhan Omar If He Can Be Part Of The Squad."

Ocasio-Cortez gladly welcomed the congressman via Twitter.

A brief history of #squadgoals

Referring to your friends as a "squad" or "#squadgoals" is common on social media. It's typically used as an aspirational term to highlight something you and your friends want to accomplish.

Rapper Waka Flocka Flame has claimed ownership of the term "squad," which he and rapper Gucci Mane have been including in their lyrics since the founding of their record label in 2007, according to Slate.

The hashtag began to gain traction on social media in 2015, when Taylor Swift popularized the slogan during her world tour that year.

Tlaib: 'I'm not going nowhere, not until I impeach' Trump

Poll: Many Americans have never heard of the 'the Squad'

Waka Flocka Flame tweeted on the subject in 2015, when some began attributing the popularization of the term to Swift.

Regardless of its origins, squad goals no longer just applies to Instagram. It's become tied to perhaps the four most visible freshman congresswomen in America.

USA TODAY's William Cummings and Rebecca Morin contributed reporting. Follow Grace Hauck on Twitter @grace_hauck.

This article originally appeared on USA TODAY: The Squad in Congress: How AOC, Omar, Tlaib and Pressley got the name