Teaching Baldrick to count, especially the last line (Season 2 - Head).
Watching the Season 2 ep. Beer when it was first on TV was probably the hardest I’ve ever laughed at a TV show, especially the reveal of the turnip and:
Melchett: Field Marshal Haig has formulated a brilliant new tactical plan to ensure final victory in the field.
Blackadder: Ah. Would this brilliant plan involve us climbing out of our trenches and walking very slowly towards the enemy?
Captain Darling: How could you possibly know that, Blackadder? It’s classified information!
Blackadder: It’s the same plan that we used last time and the seventeen times before that.
Melchett: Exactly! And that is what is so brilliant about it! It will catch the watchful Hun totally off guard! Doing precisely what we’ve done eighteen times before is exactly the last thing they’ll expect us to do this time! There is, however, one small problem.
Blackadder: That everyone always gets slaughtered in the first ten seconds.
Melchett: That’s right. And Field Marshal Haig is worried this may be depressing the men a tad. So he’s looking for a way to cheer them up.
Blackadder: Well, his resignation and suicide seems the obvious choice.
Melchett: Hmm, interesting thought. Make a note of it, Darling.
Blackadder: Get the door, Baldrick.
[There is a crash. Baldrick enters, carrying a door.]
Blackadder: Baldrick, I would advise you to make the explanation you are about to give… *phenomenally *good.
Baldrick: You said “Get the door.”
Blackadder: Not good enough. You’re fired.
Baldrick: But my lord, I’ve been in your family since 1532!
Blackadder: So has syphilis! Now get out!
Edmund: “Then I’ll probably drop her, and get two hundred concubines to share my bed.”
Baldrick: “Won’t they be rather prickly?”
Oh lord, I love that whole episode. Great Boo’s up. Awesome. And the way he mentally walks through to get to it is physical comedy genius.
And;
“Chair! You have chairs in your house?”
“Oh…yes”
“Wicked child! (smacks Blackadder) Chairs are the invention of Satan! In our house, Nathaniel sits on a spike!”
“And yourself?”
“I sit on Nathaniel. Two spikes would be an extravagance!”
Always made me wonder how many takes those scenes took. Also, I try to imagine what the actress’s reaction was when she first saw the script.
(paraphrased slightly)
Blackadder: Baldrick, do you have no idea what irony is?
Baldrick; Yes, my Lord. It’s like goldy or bronzy, but made of iron.
Yeah, one of those shows where the script is excellent but the delivery and timing elevate it to greatness.
Agreed - that is an absolute masterpiece (the whole episode, and that moment in particular).
Sorry, all cast 
But I’m glad you’re interested in attending! (If you go to the page I linked earlier, you can see a few photos from when we did Season 2 a few years ago).
Best bit of comedy in the history of humanity.
Vincent Hanna: Prince George … who is described in his party news-sheet as a great moral and spiritual leader of the nation; but is described by almost everyone else as a fat flatulent git.
and
Blackadder: Right. Now all we have to do is fill in this MP application form. Name:
Baldrick. First name…? Er, I’m not sure.
Blackadder: Well, you must have some idea…
Baldrick: Well, it might be Sod off.
Blackadder: What?
Baldrick: Well, when I used to play in the gutter, I used to say to the other snipes, “Hello, my name’s Baldrick,” and they’d say, “Yes, we know. Sod off, Baldrick.”
and then…
Vincent Hanna: Well perhaps he can answer one question: What does the ‘S’ in his name stand for?
Blackadder: Sod off.
Vincent Hanna: Fair enough. None of my business really.
Above is my favorite scene from “Potato”. I think every line BA ever said is utterly classic, but it’s great to see him try to stand up to our sea captain.
"“You have a woman’s hand, milord! I’ll wager these dainty pinkies never weighed anchor in a storm.”
“Your skin milord. I’ll wager it ne’er felt the lash of a cat [‘o’ nine tails], been rubbed with salt, and then flayed off by a pirate chief to make fine stockings for his best cabin boy.”
“Ha. -Aah! You have a woman’s purse! I’ll wager that purse has never been used as a rowing-boat. I’ll wager it’s never had sixteen shipwrecked mariners tossing in it.”
"Oh! You have a woman’s mouth, milord! I’ll wager that mouth never had to chew through the side of a ship to escape the dreadful spindly killer fish. " 
From the same ep:
Sir Walter: Oh yes? And who will be your captain? Hmph! To my mind, there is only one seafarer with few enough marbles to attempt that journey.
Edmund: Ah yes, and who is that?
Sir Walter: Why, Rum, of course. Captain Redbeard Rum.
Edmund: Well done. Just testing. And where would I find him on a Tuesday?
Sir Walter: Well, if I remember his habits, he’s usually up the Old Sea Dog.
Edmund: Ah yes, and where is the Old Sea Dog?
Sir Walter: Well, on Tuesdays he’s normally in bed with the Captain.
From the same, again:
Percy: “Because we’ll never get home. We’re doomed, doomed! Condemned to a watery grave with a captain who’s legless-”
Captain Rum: “Rubbish! I’ve hardly touched a drop!”
Percy: “-No, no. I mean you haven’t got any legs.”
Rum: “Oh, yes, you’re right there. Carry on, sorry.”
Edmund: Baldrick you wouldn’t know a subtle plan if it stripped itself naked and danced on top of a harpsichord singing, “Subtle Plans Are Here Again”.
Every Christmas I like to wish everyone a “Merry Messy Kweznuz.”
For a while my sig was:
“…there’s nothing more likely to stop an inheritance than a thingy-shaped turnip.”
One thing to notice, this is why mobile links have to be avoided, apps really do not work well in the desk top, I get an error as it tries to play a video in mobile 3gp format. Here is the link to the clip in desktop mode:
Honestly, though, the best parts are always the songs at the end of the episodes.
I was reminded of this excellent Flashheart line last night:
Flashheart: “Just because I can give multiple orgasms to the furniture just by sitting on it doesn’t mean I’m not sick of this damn war. The blood, the noise, the endless poetry…”
I was once late to a staff meeting at work and my boss looked up and asked, “Where have YOU been?” I immediately threw out my chest and boldly asked back, “WHERE HAVEN’T I BEEN?”
Took the edge off of the moment.