Must-Watch VIDEO: TONIGHT SHOW Outtake - After Goofs, Jimmy Fallon Joins Barbra Streisand & Alec Baldwin for Duet!

In this hilarious outtake from last Thursday's TONIGHT SHOW STARRING JIMMY FALLON, Barbra Streisand and Alec Baldwin turned their duet of "The Best Thing That Ever Has Happened" into a trio when they both get a case of the giggles and invite Jimmy Fallon to sing along in this special performance that never made it to air!

Streisand's new album "ENCORE: Movie Partners Sing Broadway" was released on Friday, August 26th. "ENCORE" features 10 new Streisand duets of Broadway classics with some of the biggest stars in Hollywood. The inspired new musical pairings include Alec Baldwin, Antonio Banderas,Jamie Foxx, Anne Hathaway, Hugh Jackman, Seth MacFarlane, Melissa McCarthy,Chris Pine,Daisy Ridley, Patrick Wilson, and a spectacular virtual duet with Anthony Newley.

Streisand is the only artist ever to receive Oscar, Tony, Emmy, Grammy, Directors Guild of America, Golden Globe, National Medal of Arts and Peabody Awards and France's Légion d'Honneur as well as the American Film Institute's Lifetime Achievement Award. She is also the first female film director to receive the KENNEDY Center Honors. In 2015, President Barack Obama presented her with the highest civilian honor the United States bestows, the Presidential Medal of Freedom.

She won Oscars for both Best Actress ("Funny Girl") and Best Original Song (for her composition of "Evergreen" which has since become a standard.) She also was nominated for Best Actress for "The Way We Were." The three films she directed received 14 Oscar nominations. Her recordings have earned her ten Grammy Awards, including and Grammy's Lifetime Achievement and Legend Awards.