McDonald’s restaurants aired television commercials for its “Big Mac” sandwich in January 2013; the theme was “Think with your mouth.” The words “mouthinking,” “mouthinker” and “mouthopia” were also introduced in the commercials.
 
“Can you think with your mouth open?” was asked in 1925 and “You can think with your mouth shut?” in 1931. The saying was that one should stop talking and start thinking (before talking again). McDonald’s “Think with your mouth” has nothing to do with talking—it means that one should make food choices based upon taste.
 
 
Wikipedia: Big Mac
The Big Mac (introduced in metro Pittsburgh in 1967 and nationwide in 1968) is a hamburger sold by McDonald’s, an international fast food restaurant chain. It is one of the company’s signature products. It consists of two 1.6 oz (45.4 g) 100 per cent beef patties, American cheese, “special sauce” (a sort of Thousand Island dressing), iceberg lettuce, pickles, and onions, served in a three-part sesame seed bun.
 
YouTube
McDonald’s
Think With Your Mouth
 
Google Books
Automobile Selling Sense;
A book on the merchandising of motor cars, prepared in the good interest of distributor, dealer, and salesman, with the ambition to aid in more effective sales-making,
By Cliff Knoble
New York, NY: Prentice-Hall, Inc.
1925
Pg. 103:
Can You Think With Your Mouth Open?
Many a salesman is handicapped because his mouth emits little but hot air.
   
Google Books
A Handbook of Child Psychology
By Carl Murchison and John E. Anderson
Worcester, MA: Clark University Press; London: H. Milford, Oxford University Press
1931
Pg. 378:
“But,” we objected, “you can think with your mouth shut?” “No.”
 
The New York Egotist
Translation wants you to “Think With Your Mouth” in these spots for McDonalds.
by The New York Egotist 1/15/2013 12:00pm
Translation has developed four new spots for McDonald’s as part of the “Think With Your Mouth” campaign, designed to reinvigorate the iconic status of the Big Mac.

The four spots, entitled “Sexy Music,” “Mouth Soiree,” “Attack,” and “Mouthopia” are designed to “get consumers talking about the Big Mac again”. These 15-second spots are step one of a larger campaign, set to launch over the coming month.
 
Awful Advertising
MCDONALD’S IS GOING RETRO WITH THEIR ADVERTISING
Written by David Rogers on Friday, 18 January 2013 09:33.
Boy, advertising sure was a bit wacky 30-40 years ago, wasn’t it? What’s that? This McDonald’s ad was just loaded to the company’s YouTube page on January 15th, 2013? Well, that makes things a bit more interesting.
(...)
Ironically, the company is still trying to use their modern advertising mumbo-jumbo in the description of the video, claiming you should be a “mouthinker” and “think with your mouth”. I think we’ll just stick to watching all the cool lasers.
 
warmonderhof
MOUTHOPIA
Posted on januari 24, 2013 door warmonderhof
Are you mouthinker enough to start thinking with your mouth? Mouthinking is a concept that’s easy to understand—pick up a Big Mac. And then eat it. Now you’re thinking with your mouth. TWYM.
 
68ANNE’s Sparkpage
Do not think with your mouth
Monday, March 11, 2013
I saw a commercial tonight for a certain fast food chain. It shows their signature burger floating in space talking about how your mouth would love it or something like that. It ends with ‘think with your mouth’ and I am so totally disgusted! So I’m watching this and my stomach is going yuck, because it remembers how it felt last time I thought I could eat one of those horrible things. This is epiphany for me. Realizing that my brain and it’s hormones are no longer driving my eating habits. My stomach is what decides (most of the time) what I am going to eat and I’m loving it.
 
Twitter
Beth Grossman
‏@BethRGrossman
Mouthinking leads to mouthsinging. #BigMac - http://nib.ly/fwre
Big Mac - “Dream”
We’re not sure what you dream about. But, we’re confident that your mouth probably dreams about Big Macs and singing space wizards. Want proof? Just watch.
View on web
10:09 AM - 26 Mar 13