butt bags

Noun

butt bag (plural butt bags)

1. (Canada, US, informal) A fanny pack.
   • Each carried a shielded crimson dive light, invisible from the surface, which gave objects a gray, pallid distortion. They were also equipped with a knife strapped to one calf, a small P-6 pistol holstered on the other, a compact butt bag of tools, and a short bang stick armed with a twelve-gauge...1990, Charles Ryan, The capricorn quadrant, →ISBN, page 15
2. A seat attached to ropes on which a climber can sit while belaying.
   • An alpine hammer, which has seen better days but never ice, slots into his holster. A wire brush, a nut pick, jumars and etriers all clip onto his harness and his butt bag (belay seat) goes into his pocket.1986, New Zealand Alpine Journal - Volume 39, page 113