There are a lot of Billy Joel fans out there, but we're sure most of them never expect to sing one of the rocker's songs in front of him!

That's exactly what happened to a group of elementary school students when the Grammy winner unexpectedly showed up to their spring concert called, "The River of Dreams: A Billy Joel Tribute."

"We invited Billy Joel on a lark, but we didn't expect him to come," Deasy Elementary School principal Nomi Rosen said. "It was totally thrilling. We were all beside ourselves."

billy joel

The performance took place in Glen Cove, N.Y., about a 10-minute drive from Billy's Centre Island, N.Y. home. The pianist arrived on his motorcycle and chose to take a seat in the back.

"I asked him if he wanted to sit in front, but he said he would rather stay in the back so he wouldn't make the kids nervous," Nomi shared.

Music teacher Rosita Mallo told Newsday she found out two minutes before the concert began the man himself was in the building. "It totally freaked me out," Rosita admitted. "My nerves went sky-high."

To ensure the spotlight stayed on the kids, the 64-year-old made an early exit after listening to a few songs. He was caught on camera clapping enthusiastically after a performance of "Uptown Girl."

Watch a clip from the performance below featuring a few camera pans to Billy!