In 1987, friends Billie Joe Armstrong and Mike Dirnt, 15 years old at the time, formed a band called Sweet Children. The first Sweet Children show took place on October 17, 1987, at Rod's Hickory Pit in Vallejo, California where Armstrong's mother was working. In 1988, Armstrong and Dirnt began working with former Isocracy drummer, John Kiffmeyer (also known as Al Sobrante). Kiffmeyer served as both the band's drummer and business manager, handling the booking of shows and helping the band establish a fan base. Lookout! released Green Day's first LP, 39/Smooth in early 1990. Green Day recorded two EPs later that year: Slappy and Sweet Children, the latter of which included some older songs they had recorded for Minneapolis indie label Skene! Records. In 1991, Lookout! Records released 1,039/Smoothed Out Slappy Hours, a compilation of the 39/Smooth, Slappy, and 1,000 Hours EPs. In late 1990, shortly after the band's first nationwide tour, Sobrante left the East Bay area to attend college. The Lookouts drummer Tré Cool began filling in as a temporary replacement, and when it became clear that Sobrante did not plan to commit to the band full time, Tré Cool's position as Green Day's drummer became permanent. The band went on tour for most of 1992 and 1993, and played a stretch of shows overseas in Europe. The band's second full length album Kerplunk sold about 50,000 copies in the U.S. Kerplunk's underground success led to a wave of interest coming from major record labels, and they eventually left Lookout! on friendly terms and signed with Reprise Records after attracting the attention of producer Rob Cavallo. Signing to Reprise caused many punk rock fans to regard Green Day as sellouts. Reflecting on the period, Armstrong told Spin magazine in 1999, "I couldn't go back to the punk scene, whether we were the biggest success in the world or the biggest failure ... The only thing I could do was get on my bike and go forward." After signing with Reprise, the band went to work on recording its major label debut, Dookie. Green Day's sound is often compared to first wave punk bands such as the Ramones, The Clash, Sex Pistols, The Jam, and the Buzzcocks. The majority of their song catalog is composed of overdriven guitar, fast, manic drums, and relatively high-treble bass. Most of their songs are fast-paced and under four minutes. Billie Joe Armstrong has mentioned that some of his biggest influences are seminal alternative rock bands Hüsker Dü and The Replacements, and that their influence is particularly noted in the band's chord changes in songs. In fact, Green Day has covered Hüsker Dü's "Don't Want to Know If You Are Lonely" as a B-side for the "Warning" single, and the character "Mr. Whirly" in their song "Misery" is a reference to the Replacements song of the same name.