Having just finished his autobiography I'll borrow a couple of David Niven's brown job stories.
In the inter-war years as a young officer Niven was instructed to attend a training presentation on the latest version of the Vickers machine gun, the training session was delivered by a stuffy old WWI officer who droned endlessly on about fields of fire and aiming point deflection. After several hours of this he finally wrapped up his presentation and asked if there were any questions - Niven raised his hand and asked "yes, do you have the time sir, you see I have a train to catch".
He was placed under close arrest for that little crack with the threat of a Court Martial - his "guard" allowed him to escape and Niven resigned his commission by letter that same day and left to pursue his acting career in the US, later returning to the UK to fight in WWII of course.
Following his return he volunteered for "special duties" at a training base in Scotland, duties which turned out to be a fledgling commando unit. His "recreation" took the form of a rather buxom Danish model living in London - having been given a 72 hour pass he sent her the following telegram "am on my way, will be bringing secret weapon with me, be ready". As he arrived outside the door of her flat 2 rather large gentlemen in hats and long coats appeared from the shadows and asked him to accompany them to the station. He was locked in an interview room and asked why he was discussing "secret weapons" with a foreign national and potential Nazi sympathiser, he explained that "oh this isn't about secret weapons old chap, it's about f()#king !!".