Taylor Swift Surprises Best Friend with Dashboard Confessional Sing-along

Paramore's Hayley Williams was also at the birthday bash!

Taylor Swift knows how to throw a surprise party.

The "Style" singer hosted a birthday bash for her childhood best friend Abigail, who turned 25, and caused her gal pal's mouth to drop when she had her favorite high school singer step out with guitar in hand. "Her favorite all-time band and still is Dashboard Confessional," Swift revealed to a packed house. "I'm just asking a random question, do we have anyone here named Chris Carrabba?"

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That's when Carrabba, lead singer of Dashboard Confessional, stepped out of the crowd.

The party guests then went into a sing-along with the rocker of his emo hit "Hands Down."

The guest list for Abigail's birthday was star-studded. Paramore's Hayley Williams, the Followill brothers from Kings of Leon and supermodel Lily Aldridge were all in attendance.

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And it wouldn't be a party without a photo booth! Swift also shared a slew of silly posed pics.

The 25-year-old singer's Easter weekend also included an egg hunt with her brother Austin. "When your parents arrange a competitive sibling Easter egg hunt, failing to take into account that their children are Ross and Monica," she Instagrammed. "I'VE GOT LIKE A HUNDRED GOOD LUCK."

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One person that was noticeably missing from the weekend's festivities was Swift's rumored new boyfriend Calvin Harris. The two were, however, spotted holding hands in West Hollywood this past week. Check out the video for more details of their date night.