That one still cracks me up.
I’m surprised nobody has mentioned the Backyard Catapult or the Amazin’ Laser. How can you forget the how he demonstrates that it is “100% pure lexon plastic” by taking it through an airport metal detector.
“Please do not buy the Amazin Laser.”
Otto, you’ll be pleased to know that at your very first post I though “Wow, are you me?” (which is not to say that being me is all that great, but I did think I had kinda cornered the market on that), and even got irritated that you had posted the one I was just warming up my fingers for.
You’re not invisible, sweetie. You’re just too white-hot brilliant for the lesser minds to grasp.
Wow, we’ve got all my favorites already… except!
NCI - the Long distance company that really wants your business.
Customer (Phil Hartman) : “Will you kill my boss?”
Rep (David Spade) : “No. Absolutely not. "
Customer : “I want a long distance company that will kill my boss…”
Rep : pause " Allright, if you switch to NCI now…”
And don’t forget Steve Martin’s penis cream.
Bad Idea Jeans was mentioned already - “I thought about wearing a condom, but then I figured ‘hey’, when I am going to be in Haiti again?”
Old Glory Insurance - “Remember, robots need old people medicine to survive. If someone tells you you don’t need this insurance, they have already been replaced by a robot.”
I can’t find any info on the sketch, but my other favorite was for the car designed by the insane. It talked about how it would crumple at the slightest impact, that it ran on bald eagle heads, stuff like that.
Jewess Jeans
and
The Royale (the car with a ride so smooth that you could perform a bris in the backseat).
There was one for a luxury sedan that proved how smooth the ride was by having a moehl perform a circumcision in the back seat. Shots cutting back and forth of rough bumpy roads and the moehl, with one particulary big pothole punctuated by a baby’s cry.
“How was it, rabbi?” “Poifect!”
And then there were the quickie adverts that led into Weekend Update, along the lines of “Weekend Update, brought to you by Hershey Highway, the candy that’s been turning America’s tastes around for years!”
The Love Toilet – a romantic toilet for two, so you never have to leave your beloved. Featuring Kevin Nealon and (I believe) Victoria Jackson lovingly holding hands and gazing into each other’s eyes, with their red silk undies around their ankles.
Jiffy Express – When it absolutely, positively had to be there three weeks ago. (They “age” your package with tire tracks and overseas labels so it looks like it got lost.)
Straight Dope Classic (about 3/4 of the way down): http://www.straightdope.com/classics/a3_104.html
“1-800-HARASSS. The extra ‘S’ is for extra harassment”.
and
“Brought to you by Mutual Life, because YOU could die tomorrow”.
Oh! I forgot the name on this one, but it was for a delivery service which damaged packages (dropped them in water, stamped fake tire tracks on them, etc) if you were late shipping your item. The tag line was “When it has to be there tomorrow, call the other guys. When it had to be there yesterday, call us! We’ll take the package…and the blame!”
I’m cracking up at some of these I’ve forgotten.
But y’all missed “F’ed Up Malt Liquor.” The one where an actual fist came out of the can and punched you in the face, lol.
Psst . . . check three posts up from yours . . .
“The Jiffy-Pop Airbag”
Another luxury car one, I can’t remember the name, but it ended with someone (I think it was Will Ferrell) looking around, seeing no one, then dropping his pants and having sex with the car (the rear license plate flipped down, you see, and behind it was…).
It was “The Mistress.”
A good one that hasn’t been mentioned yet is Wilson Trap Doors–a must for any corporate crook.
Also, Uncle Jemima’s Pure Mash Liquor (A nice touch was having “Uncle Jemima” occasionally swat at animated birds then animated pigs and, by the end, animated bats that only he saw.)
Not a product, per se, but a parody of a real ad that had me fooled until the very end. It was when the Navy was running their “It’s not a job, it’s an adventure” campaign showing liberty in exotic locales. This one was “Port of call, Bayonne, New Jersey” I was still going, “Wha-a-a?” when the tag came on. “It’s not a job, it’s $125 a week.”
DD
I loved this fake Buddweiser ad when it came out with Joe Piscopo and Robin Williams. It doesn’t read nearly as well as it views, because it’t hard to communicate the fight, and the surprise of Williams decking Piscopo.
Sheesh, first with that Harry Potter scene, and now with this. I’ve got to do a better job at reviewing threads.
My favorite was the car (the Chameleon) that was burglar proof – because it looked so junky, no one would steal it. But I do see that Happy and Bryan mentioned it.
By the way, cm, I posted above about the delivery service – oh, wait, no I didn’t, that was the other topic in the other thread. 
(To be fair, I think you gave more detail in your post in this thread than Scarlett. That was a good one, also.)
Steve Martin had a bit for ass gasket in a can called Rise.
There was also something that was really more a skit about an ad agency stumped by a difficult product to sell - Okra Cola.