The story
From the airdropped ballistic projectile model "Lazy Dog", generalized to all steel airdropped kinetic bombardment ballistic projectiles.
Etymology from Wiktionary, CC BY-SA 4.0.
lazy dog bomb
Today it means: A fin-stabilized aerial-bomb-shaped solid-steel slug that is dropped from high altitude aircraft, to achieve kinetic bombardment of the targeted area below. This unpowered ballistic projectile contains no explosives and achieves its aims through kinetic energy strikes alone, typically striking at 500 mph (800 km/h). Full definition →