When David Niven joined the army during the last war [World War II] he became involved in one of those tedious military exercises carried out as rehearsals for the real thing. On this occasion, the general commanding our side thought it would be a good idea to try out the merits of homing pigeons as message carriers and rashly selected Niven for the task. Accordingly he found himself ensconced comfortably enough in a pub well behind the 'enemy' lines, from which he was supposed to send back information about troop movements. However, as the hours slipped past, nothing whatever happened, and the pigeons cooed away happily in their baskets. Finally, feeling he must justify himself in some way, Niven encoded a message, attached it to a bird's leg, and released it.
Perhaps surprisingly, it duly arrived and everyone, including the general, clustered round the signals officer while he decoded the message. It read, 'I have been sent home for pissing in my basket.'