I'm going on a limb here but I seem to recall that the cry "Rhubarb, rhubarb, rhubarb!" was used as an inflight alert by fighter pilots during the second world war to let their comrades know that there were enemy fighters in the area and a fight was imminent. I forget where I read it, so I may be mistaken but I don't think I am. Of course I look forward to any confirmation or refutation from Mudcatters in the know. Kindest reguards, Neil