Pike (sings): "Whistle while you work, Hitler is a twerp - He's half barmy, so's his army, Whistle while you work."
U-Boat Captain (pointing at Pike): "Your name will also go on zee list. What is it?"
Mainwaring: "Don't tell him, Pike!"
U-Boat Captain: "Pike."
The U-Boat Captain was an antagonist in the comedy series Dad's Army, which told the story of a group of British Home Guard as they defended Britain during World War II - he was one of several Nazi characters to be shown in the entire series but is marked as one of the more prominent in terms of antagonism.
Appearing solely in the episode "The Deadly Attachment" the U-Boat Captain appeared when the platoon was ordered to pick up the stranded crew, however due to a combination of the show's humor as well as HQ's armed escort being late the tables turn on Mainwaring and his men, who become captives of the U-Boat crew instead.
Although not really having much authority considering he and his crew were stranded the U-Boat Captain decided to play mind-games with the platoon and devised a "list" which he would add the names of people who angered him.
To further add to the already awkward nature of the situation the U-Boat Captain's main hostage was none other than A.R.P Warden Hodges - who had an infamous hatred of Mainwaring and his crew.
Captain Mainwaring is giving a lecture on parachutists and the need to determine the respective identities of British and German parachutists. This eventually ends up becoming a discussion on the possibility of refugee nuns parachuting into Britain. Mainwaring's lecture is interrupted by a telephone call from GHQ; the survivors of a sunken German U-Boat have been picked up by a fishing boat and taken to Walmington-on-Sea. The Home Guard unit is to be responsible for providing security until the proper military escort can arrive. Mainwaring, excited at finally getting to grips with the enemy, sets off with most of the platoon to collect the prisoners, but not before ordering Sergeant Wilson and Private Pike to prime the platoon's allocation of hand grenades.
Pike is naturally excited at throwing around a lot of (unprimed) hand grenades and pretending to be a gangster; Wilson is a lot more cautious, and on discovering a collection of dummy detonators along with the real charges, opts to prime the grenades with dummies, reasoning that in the event of an invasion a switch could be made quickly, as allowing certain members of the platoon to be in charge of live grenades is very dangerous.
The prisoners, including their smug and surly captain, are held in the church hall until the escort arrives. However, the escort has been delayed, meaning the Home Guard will be responsible for the prisoners overnight, including the feeding of them. Corporal Jones' suggestion of cutting the prisoners' trouser buttons off is dismissed by the U-Boat Captain as being a violation of the Geneva Convention, thus earning Mainwaring's ire; and Mainwaring proceeds to refer to Adolf Hitler as a tinpot dictator resembling Charlie Chaplin, thus annoying the captain. Mainwaring's name gets put on the U-Boat Captain's ominous "List" - a collection of names of those who have upset him, who will be brought to account once the war ends, prompting a childish exchange of "Oh no, you're not!" "Oh yes we are!" between Mainwaring and the U-Boat Captain as to which side is actually going to win the war. Pike, who foolishly opts to sing a song in which Hitler is called a "twerp" at that very moment ("Whistle while you work, Hitler is a twerp, he's half barmy, so's his army..."), finds his name also put on the U-Boat Captain's List once Mainwaring inadvertently gives it to him ("Don't tell him, Pike!").
After the prisoners receive a fish and chip supper ordered by Private Walker (including soggy chips, despite the U-Boat Captain's demands), the platoon settle down to guard the prisoners overnight. Matters are not helped by the Verger and Warden Hodges, entering the hall after a night on the drink to find the prisoners there waiting for them. Taking advantage of the distraction, the U-Boat Captain feigns illness and manages to swipe Mainwaring's pistol, seizing Hodges as a hostage.
A tense stand-off between the Germans (housed in the Vicar's office with their hostage) and the British (in the main hall with superior firepower) sees the British try to recapture the situation. A conversation about different films that ultimately goes nowhere, however, sees Mainwaring struck by inspiration; they will agree to the terms of the Germans, confident that someone in the town will see the Germans escape. Unfortunately, Mainwaring's plan is not as well thought out as the U-Boat Captain's, who has anticipated this - the platoon will be forced to march the prisoners through town to the harbour as to offset suspicion, and will then accompany the prisoners back to Germany in order to ensure that the Royal Navy do not intervene. And once they are back in Germany, the List will be closely examined. Cooperation will be further enforced by the presence of a grenade in Corporal Jones' waistband, which will have the safety pin pulled off by the U-Boat Captain at the slightest hint of trouble. Wilson gladly goes to get the grenade.
The march through town is a tense matter (for all except Wilson and Pike, who are the only ones aware that the grenade is a dud). The U-Boat captain's plan is inadvertently rumbled by Mainwaring's senior officer, the Colonel, who chances upon the marching platoon en route to meeting the escort and, seeing the string in Jones' waistband, immediately pulls it. The resulting chaos sees the Germans sprawled on the ground, Jones frantically screaming "Don't panic!" whilst dancing with a grenade in his trousers, and Wilson calmly asking the Colonel for a pistol. He promptly uses it to recapture the German Captain, forcing him and his men up against the wall. Once all has calmed down, and Mainwaring has realised that in disobeying his orders, Wilson has saved Jones' life, Jones requests if someone could ask Private Frazer to remove his hand from his trousers.