WATCH: Justin Timberlake Is the Latest Celebrity Wedding Singer!

Celebrity, Gay Marriage
Justin Timberlake and Jessica Biel's Halloween Party Details

Photo: Getty Images

Justin Timberlake sure knows how to be a great wedding guest! This Saturday, he and wife Jessica Biel attended the Norwalk, Connecticut wedding of Biel's close friend Dana Panzer, who married her longtime girlfriend Amy Wicker, Us Weekly reports. To make the occasion even more special, Biel's hubby Timberlake serenaded the newlyweds at their reception!

Although Panzer and Wicker's nuptials had been planned in advance, the wedding landed on a very exciting weekend for same-sex couples in America as it followed the U.S. Supreme Court's historic Friday decision to legalize gay marriage across the nation.

Biel and Timberlake left their two-month-old son Silas at home for the big event, which we assume allowed the new parents to let their hair down a little. Biel, who was roommates at Tufts University with Panzer, reportedly danced the night away at the wedding. One eyewitness said, "She looked amazing. You would never know she just had a baby because she is slim and trim."

See More: PHOTOS: Sofia Vergara Serves as a Bridesmaid in Her Friend's Wedding

Timberlake let loose in the best way: by showing off his vocal stylings! The Grammy-winning star offered up an extra-special wedding gift for the brides when he sat down at a keyboard and rocked out to his hit "Señorita."

"Imma start something, and all the fellahs gonna look at the ladies, who just got married tonight. And all the ladies gonna look at the ladies, you know what I'm saying," he began, as seen in the above Instagram video captured by a wedding guest. The two brides then danced as Timberlake continued to sing, busting out other songs, including "Papa's Got a Brand New Bag" by James Brown.

"Throughout the night, Justin really let loose and he started dancing in the middle of the wedding circle having an amazing time dancing to this great band," another eyewitness told Us Weekly. "Then Justin decided he wanted to put on a little concert for the two brides and he jumped on the stage. It was awesome and so special for the brides and all the guests who were so impressed!"

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