VIDEO : Taylor Swift Surprises Partygoers at a Birthday Celebration in the Hamptons

Snapchat Taylor Swift 's Saturday night was one to be remembered! Partygoers at a birthday celebration in the Hamptons over the weekend were treated to quite the treat when Taylor Swift and Nelly came together to perform the rapper's 2002 classic, "Dilemma." In multiple videos shared online, the Grammy winner can be seen having an absolute blast onstage with her newfound duet partner as she takes on Kelly Rowland 's part in the song.