CBGB's two rules were that a band must move its own equipment and play mostly original songs—that is, no cover bands—although regular bands often played one or two covers in set. CBGB's growing reputation drew more and more acts from outside New York City. In 1978, new wave songwriter Elvis Costello would open shows for The Voidoids, while The Police played at CBGB for their first American gigs. Meanwhile, CBGB became famed for the Misfits, Television, Patti Smith Group, Mink DeVille, the Dead Boys, the Dictators, the Fleshtones, the Voidoids, the Cramps, the B-52's, Blondie, Joan Jett & the Blackhearts, the Shirts, and Talking Heads. Yet in the 1980s, hardcore punk's New York underground was CBGB's mainstay. Named "thrash day" in a documentary on hardcore, Sunday at CBGB was day, which became an institution, played from afternoon until evening by hardcore bands such as Reagan Youth, Bad Brains, Beastie Boys, Agnostic Front, Murphy's Law, Cro-Mags, Leeway, Warzone, Gorilla Biscuits, Sick of It All, The Misfits, Sheer Terror, Stillborn and Youth of Today. In 1990, violence inside and outside of the venue prompted Kristal to suspend hardcore bookings, although CBGB brought hardcore back at times. CBGB's last several years had no formal bans by genre.