The old Meow Mix commercials. You know, the one where they sing it. Around the time Close Encounters of the Third Kind came out, they spoofed it with a spaceship in those Meow Mix commercials with the "Meow, meow, meow, meow" jingle. Also, 9 lives and fancy Feat cat commercials stick in my mind.
Today's commercials...the mayhem ones someone mentioned are good.
Ricardo Montalban hawking "Fine Corinthian Leather" for Chrysler. There's no such thing, it's just something they made up, but a couple of years ago a girlfriend bought a BMW and was telling me about the "Corinthian Leather" upholstery. I tried really hard not to laugh too loudly at her.
Alka Seltzer. plop, plop, fizz fizz...and "I can't believe I ate the whole thing"
"Time to make the donuts"
"reach out and touch someone" or "Have you seen our long distance bill?"
And because some ad exec got hold of my classic rock collection, I can't hear a certain Led Zeppelin song without wanting to drive a Cadillac.
Of course, nothing beats local commercials, you know the ones. Mostly car dealerships (Cal Worthington and his dog Spot, who was never a dog) and furniture stores which almost always feature their kids, a chainsaw, Telemundo wrestler, something crazy! A great local one was for Thunderbolt transmissions. I never was a huge country music fan, but for a long time I ran around in a pair of cowboy boots when I was very small singing to everyone that they didn't need a brand new car, because at Thunderbolt, they'd put the YEEHAW back in your motor and transmission.
YouTube - Thunderbolt Commercial, 1983 This shop is still around.
And of course, Discount Tire, where if you were not satisfied you could bring it back, and the little old lady throws it through the plate glass window.