mouse hole
v.— «“One man makes for the stairway, covered by bullets of the others shooting ahead of him. At the same time two or three men can enter the house and begin to ‘mouse hole’ into the next forom from the secured ground floor, while the others are securing the upper floors. Then they ‘mouse hole’ through the upper rooms.” Mouse holing, says Levy, is simple work with a pick or crowbar. You first make a small hole, toss a grenade through it, enlarge the hole and toss a second through it from inside one room or building to the next, thus making reasonably sure of disposing of everybody in the adjoining rooms.» —“Calvacade” by Charles G. Sampas Lowell Sun (Massachusetts) Oct. 30, 1942. (source: Double-Tongued Dictionary)