Plum: (and prune); the motion (and sound) of the lips spitting out the pit of a sour-sweet fruit native to much of the temperate world. A plum gives a juicier spit, hence the slower motion of rolling the pit out between the lips: plllllummmm. A prune is a firmer fruit and so can bear a sudden explosive projection of a bit, for a distance of several metres, hence the sharp sound of the word: prune! Try it. You’ll feel it.
Native Pacific Plum, Oyster Bay, Vancouver Island