Some context: Gwen Renee Stefani (; born October 3, 1969) is an American singer, songwriter, fashion designer, and actress. She is a co-founder and the lead vocalist of the band No Doubt that experienced major success after their breakthrough studio album Tragic Kingdom (1995) along with various successful singles, including "Just a Girl"
Throughout her career as a solo artist, Stefani has won several music awards, including one Grammy Award, four MTV Video Music Awards, one American Music Award, one Brit Award, and two Billboard Music Awards. With No Doubt, she has won two Grammy Awards. In 2005, Rolling Stone called her "the only true female rock star left on radio or MTV" and featured her on the magazine's cover. Stefani received the Style Icon Award at the first People Magazine Awards in 2014. Additionally in 2016, the singer was honored at the Radio Disney Music Awards with a Hero Award, which is given to artists based on their personal contributions to various charitable works.  Stefani has been referred to as a "Pop Princess" by several contemporary music critics. In 2012, VH1 listed the singer at the number thirteen on their list of "100 Greatest Women in Music". Stefani's work has influenced a number of artists and musicians including Hayley Williams of Paramore, Best Coast, Katy Perry, Kesha, Marina and the Diamonds, Stefy, Rita Ora, Sky Ferreira, and Cover Drive. The latter group, a quartet of Barbados musicians, claimed that both Stefani and No Doubt had helped influence their music, to which the lead singer of the group, Amanda Reifer, admitted that she would "pass out" if she were to ever meet Stefani.  The lead single from Love. Angel. Music. Baby., "What You Waiting For?", was considered by Pitchfork to be one of the best singles by Stefani, and would later place it at number sixteen on their "Top 50 Singles of 2004" list. Additionally, "Hollaback Girl" from the aforementioned album would go on to be the first song to digitally sell an excess of one million copies in the United States; it was certified platinum in both the United States and Australia, and peak at number forty-one on Billboard's decade-end charts for 2000-09. Since its release in 2005, "Hollaback Girl" has been called Stefani's "signature song" by Rolling Stone.
what songs did she sing?
A: The lead single from Love. Angel. Music. Baby., "What You Waiting For
Some context: David Michael Letterman (born April 12, 1947) is an American television host, comedian, writer, and producer. He hosted a late night television talk show for 33 years, beginning with the February 1, 1982, debut of Late Night with David Letterman on NBC, and ending with the May 20, 2015, broadcast of Late Show with David Letterman on CBS. In total, Letterman hosted 6,028 episodes of Late Night and Late Show, surpassing friend and mentor Johnny Carson as the longest-serving late night talk show host in American television history. In 1996 Letterman was ranked 45th on TV Guide's 50 Greatest TV Stars of All Time.
In 1975, encouraged by his then-wife Michelle and several of his Sigma Chi fraternity brothers, Letterman moved to Los Angeles, with hope of becoming a comedy writer. He and Michelle packed their belongings in his pickup truck and headed west. As of 2012, he still owned the truck. In Los Angeles, he began performing comedy at The Comedy Store. Jimmie Walker saw him on stage; with an endorsement from George Miller, Letterman joined a group of comedians whom Walker hired to write jokes for his stand-up act, a group that at various times would also include Jay Leno, Paul Mooney, Robert Schimmel, Richard Jeni, Louie Anderson, Elayne Boosler, Byron Allen, Jack Handey, and Steve Oedekerk.  By the summer of 1977, Letterman was a writer and regular on the six-week summer series The Starland Vocal Band Show, broadcast on CBS. He hosted a 1977 pilot for a game show entitled The Riddlers (that was never picked up), and co-starred in the Barry Levinson-produced comedy special Peeping Times that aired in January 1978. Later that year, Letterman was a cast member on Mary Tyler Moore's variety show, Mary. Letterman made a guest appearance on Mork & Mindy (as a parody of EST leader Werner Erhard) and appearances on game shows such as The $20,000 Pyramid, The Gong Show, Hollywood Squares, Password Plus and Liar's Club, as well as the Canadian cooking show Celebrity Cooks (November 1977), talk shows such as 90 Minutes Live (February 24 and April 14, 1978), and The Mike Douglas Show (April 3, 1979 and February 7, 1980). He was also screen tested for the lead role in the 1980 film Airplane!, a role that eventually went to Robert Hays.  His dry, sarcastic humor caught the attention of scouts for The Tonight Show Starring Johnny Carson, and Letterman was soon a regular guest on the show. Letterman became a favorite of Carson and was a regular guest host for the show beginning in 1978. Letterman credits Carson as the person who influenced his career the most.
What group did he join?
A:
a group of comedians whom Walker hired to write jokes for his stand-up act, a group that at various times would also include Jay Leno,