Unfortunately, due to the BBC repeating the clip at every possible occasion, this has actually stopped being funny to long-time fans. Which is a shame, because objectively it is a very funny line.
When Pike's actor Ian Lavender appeared on the celebrity game show Mastermind, when John Humphrys asked him his name (part of the shows format), another contestant shouted "Don't tell him Pike."
In the 2009 Star Trek reboot movie there is a tense scene in which the Romulan villain, Nero, is interrogating Kirk's predecessor, Captain William Pike, by torture. Guess what the Dad's Army fans in British cinema audiences shouted at this point.
Moments before, when the tense confrontation between Mainwaring and the U-boat Captain gets a bit... childish.
U-boat Captain: I am making notes, Captain. And your name will go on the list. And when we win the war, you will be brought to account. Mainwaring: You can put whatever you like; you're not going to win this war. U-boat Captain: Oh yes we are. Mainwaring: Oh no you're not! U-boat Captain:OH YES WE ARE!
"And when we get back to Germany, you will be my prisoners. And then ... [smugly] we shall examine the list..."
In the one where Mainwaring is marching the platoon along the watefront
Hodges: I wouldn't go too far that way Mr. Mainwaring there's a great big- (Mainwaring disapeares in a huge puddle)
When actor James Beck was taken into hospital, Walker got a Written-In Absence, leaving a note in his place on patrol to explain that he has gone to conduct "business" in London. A Crowning Moment of Funny ensues as Mainwaring reads out Walker's cockney slang in perfectly deadpan tones.
In the episode "Boots, Boots, Boots", a shoes clerk mistakes Wilson and Pike for father and son. Wilson denies it, whilst doing a face-rubbing sort of gesture, whilst behind him, Pike is (inadvertently) doing the exact same thing in synchronization!
When on watch duty in the lighthouse Jones manages to accidentally set off the light. Back on shore Hodges has the biggest freak out in the series.