Ethan Dolan squirted mustard from a restaurant-style cylinder into his 16-year-old twin brother Grayson’s mouth, and the teenage girls in the audience at the Dolan Twins’ performance at The Paramount in Huntington Sunday night erupted into screams of adoration. “Ew, I hate mustard,” Grayson yelled, causing more screaming.

It didn’t take much to get the more than 1,500 people at the event — most if not all of them teenage girls — screaming for the 16-year-old brothers known as the Dolan Twins, who are closing in on 2 million followers on YouTube, where they post comedic skits about being a teen or a twin or kooky competitions. Their videos have been viewed more than 109 million times and include such scenarios as Grayson still loopy from anesthesia after getting his wisdom teeth removed and the brothers dressing identically to prank innocent bystanders who don’t know there are two of them.

Even before The Paramount’s doors opened, the screaming began, with the girls in line for the sold out show erupting when the twins’ mother and sister appeared briefly in the theater lobby. The fans, who know everything about the twins including what their family members look like, let out more mentions of the lord than a church full of the faithful as a stream of OMGs followed.

The Dolan Twins’ stop on Long Island was part of the twins’ 40-city “4ou Tour,” and the mustard squirting was part of the twins’ onstage “Hat of Dares” challenge, during which each had to pick dares such as “eat mustard from the mustard bottle,” “say your ABCs backwards” or “wax your leg.”

Other onstage antics included a competition between the brothers to do the most pushups in 30 seconds and to maintain a handstand the longest. True to their devotion to social media, the brothers urged the crowd to photograph them and Tweet the photos to their friends.

“I thought it was amazing. I lost my voice,” said Abby Troiano, 13, of Huntington. “I love them with a passion.” Like most of the girls, she favors one over the other. “Grayson,” she said. “He’s my husband.” Abby arrived at the Paramount at 8 a.m. Sunday to be first on line to enter the venue so she could get as close to the stage as possible.

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“They’re so funny,” said Abby’s friend Isabella Dentico, 14, of Huntington. “And they’re very attractive.”

Hannah Devlin and Maria Moschos, eighth graders from Port Washington, wore matching T-shirts that said “4ou Football Team” with Ethan and Grayson’s former football team numbers on the back. Alexa Winkler, 13, of West Babylon, wrote a letter to Ethan that she planned to give to him at the post-show meet and greet. “Thank you for showing me it’s okay to act like a goofball and express myself,” Alexa wrote.