WOODBURY - Long Island’s own Piano man broke out into an impromptu doo-wop with Tonight Show host Jimmy Fallon.

During the commercial breaks of Fallon's show last night, Billy Joel and his crew busted out an un-practiced rendition of his hit "For the Longest Time."

Joining Joel is Long Island's own Mike Delguidice, who went from "Big Shot" lead singer to a member of Joel's band.

The song happened while the crew was shooting promos for the show.