Of Purina Dog Chow, of course — as seen on “Leave it to Beaver”:

As I’ve kvetched, the number one reason I hate television is that I cannot stand commercials. They do not fit in at all with the programming. Far from it; they’re as invasive as a SWAT team serving a no-knock warrant, and my response is to reach for the remote and open fire in self defense.
Commercials like the above — routine in the golden days of television — were much better because they were less invasive. They fit — as if they were part of the show. I’m sure there are many legitimate reasons why today’s commercials have to be ugly and invasive, but I won’t watch them.
But I wouldn’t turn off a commercial if it seemed like part of the show.
Why, the old commercials from the golden days of TV are so good that this calls for another Purina commercial from Leave it to Beaver!

Of course, even though they fit in with the show, the Purina commercials would be lost on some, because not everyone has a dog.
However, everyone eats, and most of us eat breakfast. Which meant that if you were a Beverly Hillbillies fan as I was, the following commercial might incline you to be an eager eater — of Kellogg’s Corn Flakes!

And what do you do after you’ve fed your dog, and eaten your Corn Flakes?
Why, if you’re an “I Love Lucy” fan, you go out and buy a new Ford.

The above convertible is “a revolution made possible by Ford’s advanced engineering!”
If Lucy can make the thing work, anyone can!
UPDATE: Second YouTube link corrected.