KBO
From Tardis Wiki, the free Doctor Who reference
Winston Churchill observed KBO, "Keep Buggering On". (TV: Victory of the Daleks)
Panda told Patrick Matthewman that he was the person who "advised Churchill to 'Keep Buggering On' in the first place". (PROSE: Project: Wildthyme)
In 1943, Wing Commander Douglas Quilter told himself to "KBO" after Jo Grant convinced him of her plan to infiltrate the manor of the occult fascist, Sir Davenport Finch. (AUDIO: Operation: Hellfire)