There is a nice story in Ralph Barker's "The RFC in France" (vol. 2) about a flight commander and observer in 48 Squadron (Bristol Fighter).
Stationed in the Dunkirk sector in autumn 1917, flight commander and pilot Capt. Samuel 'Squibs' Sibley and observer 2Lt. P.N.M. 'Puggy' Shone got bored one day so they decided to fly along the sea-front at Ostende (in occupied territory) at 50 feet and lob oranges at the off-duty Germans relaxing with their lady friends. Naturally the Germans dived for cover expecting a grenade attack as the oranges splatted onto the promenade around them. Sibley and Shone said they nearly crashed into the sea because they were laughing so much.
Contribution to the war effort: Nil
Contribution to 48 Squadron morale: Incalculable
Vigilant