"Members of a 'punk rock' band [the Sex Pistols] used a string of obscenities on a London television show Wednesday night and touched off a wave of protests from outraged viewers ... One man, trucker Jim Holme, said he was so outraged because his 7-year-old son heard the swear words that he kicked in the screen of his new $600 color TV set." Associated Press, December 2, 1976
Consistent with the scene above, Merriam-Webster describes punk rock as "marked by extreme and often deliberately offensive expressions of alienation and social discontent."
In the late 1500s, the word punk referred to a prostitute. It evolved over the centuries to become a synonym for "hoodlum" or "ruffian," which is one reason why the Sex Pistols and other influential bands adopted it in the mid '70s.