bumfyoudaoicibaDictYouDict
bumf: [20] The earliest, literal, but now long discontinued sense of bumf is ‘toilet paper’ (first recorded in 1889), which does much to elucidate its origin: it is short for bum fodder. The element of contempt is carried over into its modern meaning, ‘unwanted or uninteresting printed material’, which dates from around 1930.
bumf (n.)youdaoicibaDictYouDict
"papers, paperwork," 1889, British schoolboy slang, originally "toilet-paper," from bum-fodder.