A good clean tongue is essential to your overall health and avoiding the unpleasantness of bad breath. That is why those in the know own and use a tongue scraper—a molded plastic hook with a handle— to yank off the debris and growth from the tongue's surface. Before the Age of Plastic, tongue scrapers were made out of various metals, ivory and tortoise shell. Civilized people have been using tongue scrapers for, like, ever.
The really grody gunk is all the way in the back of your tongue. To clean that stuff, you will have to suppress your gag reflex. Just relax and exhale, you can do it without yakking. Be gentle to your tongue.
Physicians have linked crap in the mouth with increased risks to other health issues such as heart attacks, strokes, diabetes, pneumonia, osteoporosis (both of the jaw and all over), low birth weight, premature birth and male infertility (beyond the obvious). Bacteria breeds on the tongue and infiltrates other areas of the mouth through the saliva. Cleaning the tongue will thus reduce plaque, gum recession, infections and tooth decay/loss.
And if you wanted to be really clinical about shit, you could keep your tongue scraper in a special case filled with a sterile solution. I just rinse mine with hot water before and after each scrape.
If your local pharmacy does not stock tongue scrapers, try a health food store or look online. Trust me, it will be the best six bucks you ever spent.
Specialized brushes are also made for the tongue, but I have found these to be ineffective in comparison to the scraper. In a pinch, a regular tooth brush will do the trick—if you think that ruffled bristles enhances your toothbrushing experience—and there may be some who scoff at the idea of a the noble tongue scraper, saying that a brush is just fine, thanks. To those fools I can only say: apples and oranges.
A wiser soul than I has informed me that a cheap spoon will do the trick just fine. I don't see why not