I can’t remember the second verse, about Harry the mailman, but the rest is:
Eleven months throughout the year, they’re slothful as can be
But starting in December, they show great efficiency, then
Charlie and Harry, show they’re really full of zip
And they’ll work that way, every doggone day
Til they get their Christmas tip
My MAD magazine period was early to mid-nineties, but I was definitely obsessed. Like one of the posters above, I credit MAD with a lot of my critical thinking skills, but also with most of my older pop culture knowledge. I was always trying to chase down back issues, and buying the books and collections. To this day, I’ve never seen Love Story or All in the Family, but I’ll never forget their parodies (which introduced me to theatrical truism like “the heroine who gets more beautiful as she’s dying” disease).
Anyone remember J. Edgar Hoover doing Gilbert & Sullivan?
That’s entirely from memory - it is amazing what a stash of useless information I have tucked away back in the shadowy recesses of my head.
My dad had a strict “no comics of any kind” policy, probably influenced by the EC Comics/juvenile delinquency hearings in the 1950s. I remember him finding the issue with Batman and Robin on the cover and tearing it up. After that I had to devise extreme hiding places for my MAD magazines, which came in handy later on when I started reading more “adult” material.
In contrast to my home environment (see above), I had a high school teacher who thought that MAD was good for English Literature. She said you couldn’t understand a Shakespeare or Chaucer parody if you didn’t know the original, and she often read MAD in class to illustrate.
The MADs she read in class were confiscated from students. 
In that same spirit here’s the first hit I found on the MAD parody of I Wandered Lonely as a Clod
How do they reproduce the fold-ins? Do they show the before and after?
My Dad bought me my first Mad magazine, sometime in the late 70s (I guess I would have been around 9 or 10). For the next few years after that, Mad was generally my go-to purchase whenever I was at a store with a magazine rack and had any extra spending money. I’m pretty sure Mad magazine was a major influence on both my sense of humor and my view of the adult world and popular culture.
My mom’s rule was that anytime we saw a new issue of * Mad* she would buy it for us.
I love my mom.
I grew up through the 1960s and 70s, so of course I grew up reading Mad Magazine. While I haven’t looked at one for a long time, I remember it very fondly. About 15 years ago I picked up a copy of Bedside Mad at a secondhand book store, and I still have it. I think it was just about the first ever Mad paperback book, and it includes a couple of the earliest movie parodies–“Hah! Noon” and “The Cane Mutiny”. Among other things there are additional items that hearken back to the magazine’s comic-horror roots, and a delightful take on Robinson Crusoe, which everyone either read in school, or was supposed to have read. The RC story (“RC” to use the license plate of his handmade automobile) includes what is probably the earliest Dragnet spoof, for his man Friday turns out to be that Friday.
I had the book when I was a kid, too, but lost it somewhere along the way.
They do have the before and after; the actual “folding” is animated. There’s an early one featuring the Beatles that doesn’t work because it folds diagonally.
I have the earlier 7-CD set.
Fan since 67. Used to collect the mags, books, etc. They still make me laugh. Quality humor will do that.
The DVD edition I have has the folded version as a separate PDF that appears when you click on the unfolded version. The diagonal Beatles page naturally works properly on this one.
My brother has some of the oldest ones, in comic book format. They still have an edge 60ish years later.
An “ad”:
A puzzle page parodied rebuses [E. g., (picture of a cat) + SUP = CATSUP]
One puzzle showed not just plus signs and minus signs, but also multiplication and division. Along with impossible-to-identify drawings looking like machine parts.
Yet another puzzle page showed variations on the “What’s wrong with this picture” theme.
One such had people listening to a TV and watching a radio, etc.
The solution read: “A better question would be, what’s right with this picture?”
The most memorable clue in the picture was a newspaper headline reading, Liberace Wins by KO in 9th
I wish there was a big slick book of all the original comic book Mads.
I remember once (I believe in the 50’s or early 60’s) they ran a very precient parody ad for a weight loss system called Nu-Mal Nutrition:
"It has no harmful chemicals to hurt you. It has no bothersome hormones to mess up your system.
It simply knocks you unconscious for days on end."
Man, would that stuff sell today. I always smile whenever I see weight loss commercials now.
There is. The four volume Mad Archives set.