Question: Pat Smear joined what American rock band, co-founded by Kurt Cobain, as a touring guitarist?
Context: The discography of Foo Fighters, an American rock band formed in 1994 by Dave Grohl, consists of nine studio albums, four extended plays (EPs), six video albums, and 36 singles.  The current Foo Fighters line-up consists of Grohl (vocals and guitar), Taylor Hawkins (drums), Rami Jaffee (keyboard), Nate Mendel (bass), Chris Shiflett (guitar), and Pat Smear (guitar). Nirvana was an American rock band formed by singer and guitarist Kurt Cobain and bassist Krist Novoselic in Aberdeen, Washington, in 1987.  Nirvana went through a succession of drummers, the longest-lasting being Dave Grohl, who joined in 1990.  Despite releasing only three full-length studio albums in their seven-year career, Nirvana has come to be regarded as one of the most influential and important alternative bands in history.  Though the band dissolved in 1994 after the death of Cobain, their music maintains a popular following and continues to influence modern rock and roll culture. Jason White (born November 11, 1973) is an American musician, best known as the current touring guitarist for the American punk rock band Green Day.  He has played as a touring member of Green Day since 1999.  However, in 2012, he was promoted to being an official member of the band before demoting himself back to his touring guitarist role in 2016.  He is also the guitarist/vocalist for the Californian punk band Pinhead Gunpowder, lead guitarist/lead vocalist for California, and co-founder of Adeline Records alongside Billie Joe Armstrong. Wasting Light is the seventh studio album by American rock band Foo Fighters.  It was released on April 12, 2011 on RCA Records, and is the first album to feature rhythm guitarist Pat Smear since "The Colour and the Shape" (1997), making the band a five piece with the album.  Wishing to capture the essence of the group's earlier work and avoid the artificiality of digital recording, frontman Dave Grohl arranged for the band to record in his garage in Encino, California using only analog equipment.  The sessions were supervised by producer Butch Vig, with whom Grohl had worked on Nirvana's "Nevermind".  Since the old equipment did not allow for many mistakes to be corrected in post-production, the band spent three weeks rehearsing the songs, and Vig had to relearn outdated editing techniques.  The band went for a heavier and rawer sound to contrast with the musical experiments from their previous albums, and most of the lyrics were written as Grohl reflected upon his life and possible future.  Guest musicians include Bob Mould, Krist Novoselic, Jessy Greene, Rami Jaffe and Fee Waybill. Nirvana was an American rock band formed by singer/guitarist Kurt Cobain and bassist Krist Novoselic in Aberdeen, Washington in 1987, with drummer Dave Grohl joining the band in 1990.  Though their brief run ended following the death of Kurt Cobain in 1994, Nirvana has come to be regarded as one of the most influential and important rock bands of the modern era. Darby Crash (formerly Bobby Pyn; born Jan Paul Beahm; September 26, 1958 – December 7, 1980) was an American punk rock vocalist and songwriter who, along with long-time friend Pat Smear (born Georg Ruthenberg), co-founded the punk rock band the Germs.  He committed suicide by way of an intentional heroin overdose.  In the years since his suicide at the age of 22, the Germs have attained legendary status among punk rock fans and musicians alike, as well as from the wider alternative rock and underground music community in general.  Crash has come to be revered as a unique and talented songwriter; his myriad literary, musical and philosophical influences, which varied from Friedrich Nietzsche and David Bowie to Charles Manson and Adolf Hitler, resulted in lyrics that were unusually wordy and impressionistic in the realm of punk rock at the time, immediately setting Crash and his band apart from most other Los Angeles punk groups that sprang up in the late 1970s. Foo Fighters is an American alternative rock band formed by multi-instrumentalist and vocalist Dave Grohl in 1994.  After recording the album "Foo Fighters" alone, Grohl enlisted guitarist Pat Smear, bassist Nate Mendel and drummer William Goldsmith to join the band.  This lineup recorded the second Foo Fighters album, 1997's "The Colour and the Shape", although most of Goldsmith's drum recordings were removed and re-recorded by Grohl for the release, after he left the band due to creative tensions.  Goldsmith was replaced by Taylor Hawkins, and Franz Stahl replaced Smear after he also departed, although he only remained in the band for a short period and did not record an album with the group.  The group's third album, "There Is Nothing Left to Lose", featured Hawkins on drums and was released in 1999. The Germs were an American punk rock band from Los Angeles, California, United States, originally active from 1977 to 1980.  The band's main early lineup consisted of singer Darby Crash, guitarist Pat Smear, bassist Lorna Doom and drummer Don Bolles.  They released only one album, 1979's "(GI)", produced by Joan Jett, and were featured the following year in Penelope Spheeris' documentary film "The Decline of Western Civilization", which chronicled the Los Angeles punk movement. Georg Albert Ruthenberg (born August 5, 1959), better known by the stage name Pat Smear, is an American guitarist and occasional actor.  Smear was a founding member of the influential punk band the Germs, and was the additional live rhythm guitarist for the grunge band Nirvana.  He currently plays guitar in the rock band Foo Fighters, with whom he has recorded three studio albums and a live album. So You Fell In Love With A Musician... is the second solo album by guitarist Pat Smear, released by SST Records in 1992.  A music video, filmed by Dave Markey, was made for the song "Innocent X".  The year following this album's release, Smear joined grunge band Nirvana as a touring guitarist.
Answer: Nirvana