Reverse Psycho

Most commercials will tell you to buy their product. However, there's a small subset of commercials that implore you not to buy the product advertised, because it's harming the person or thing making the plea. Won't you please think of us and don't buy this wonderful product?

An attempt by ad executives at Reverse Psychology. Call it one of the "perks" of living in a post-modern world, and try not to follow the chocolate bunnies' example over it. See also Talking Pest.

(This trope has nothing to do with hot girls killing schizophrenic men in a shower, by the way. If that's what you're into, watch Hard Candy, but Your Mileage May Vary)

Entertainment

 * The "Boycott Spyro..." campaign for the first game in the series, led (more like single-handedly run) by a grouchy anthropomorphic sheep. Like the probable response towards this entry, no one really cares.
 * Earthbound. It stinks.

Food and Drink

 * Extra Polar Ice chewing gum had a series of ads where several young men claimed chewing Extra would... mutate you into a polar bear. Seriously.
 * ...and then the people who make Stride Gum encourage people to "start chewing that second piece" because sales have plummeted and workers are breakdancing in the factory to pass the time.
 * Which was followed by commercials in which representatives from the company are forcibly removing that first piece of gum (in humorous ways such as a ram head-butting a guy in the stomach out of nowhere), accompanied by the tagline, "Spit out your Stride gum and chew another piece already -- or we'll find you." Because threats of violence are sure to improve sales.
 * The ice cream franchise Gelazzi advertises its chocolate with the tagline "makes all other chocolate feel hopelessly inadequate", and photos depicting chocolate bunnies attempting suicide in various ways.
 * Jim Henson was responsible for an early example of this in his pre-Muppet Show days. He produced a series of commercials for Wilkins Coffee, featuring two characters: Wilkins, who loves the coffee, and Won'tkins, who hates it and tells the audience not to buy it.
 * Which usually ends in Won'tkins getting maimed in a highly amusing fashion.
 * During the '90s foul brewing byproduct Marmite had an "I Hate Marmite" version of its "My Mate Marmite" adverts. (Their current "You either love it or hate it" adverts continue to admit that sane people hate the stuff).
 * One mayonnaise commercial features turkeys seeing a turkey's presentation and panicking over how the brand makes a better... turkey sandwich.

Furniture and Housewares

 * Serta mattress's "Counting Sheep" commercials, where the mattress is so comfortable the sheep (which people would normally count in order to get to sleep) urge people not to buy Serta mattresses because they are losing their jobs.
 * One of the earliest examples features a forlorn Maytag repair man, who never has anything to do, as Maytag equipment never breaks down.
 * This series has gone on so long they seem to have got worried about the actor's age; a young apprentice repairman with a neurotic dedication to makework was introduced.
 * According to Wikipedia, Jesse White played the original repairman in 1967, followed by Gordon Jump from 1989-2003. White died in 1997; Jump died in 2003. Demographics wasn't the only factor.
 * The workless Maytag repair men commercials were harshly parodied in Robot Chicken, where the out-of-work repair man goes home to a screaming wife and have a huge argument.
 * Many of Sit 'n Sleep's ads feature the boss Larry and his "accountant Irwin", whose reaction to their various offers is invariably "You're killing me, Larry!"

Hygiene

 * Another early example was Mr. Whipple, the Charmin salesman, who once became infuriated whenever potential customers squeezed the Charmin to test its softness. ("PLEASE DON'T SQUEEZE THE CHARMIN!") Eventually he saw the light.

Restaurants

 * Inversion along the same principle: Chick-fil-A, a fast-food restaurant chain that specializes in chicken products with a side of religious right, has ads with normal cows imploring people to eat chicken, not burgers or other beef products, complete with crudely-painted signs with bad spelling (because cows are dumb and can't type/write/paint well with hooves).
 * Eat Mor Chikin!
 * Burger King had a Chicken Run promotion that used a similar tactic, with the movie chickens telling people driving by the farm to eat more beef to save them.
 * McDonald's tried this a few years ago with their "Arch Deluxe" sandwich as a way to appeal to the more mature crowd, as opposed to their long-standing "appeal to kids" philosophy. They had a huge advertising campaign showing how repulsed children were at the new sandwiches. It didn't work out so well, and other fast-food restaurants started to make fun of them in their commercials.

Sports

 * Callaway Golf had a series of commercials where an old-school golfer played by John Cleese implores you not to buy their golf balls because they make the game of golf too easy.

Technology

 * The internet provider Comcast runs a series of commercials based on the Slowskys, a couple of turtles who are disgruntled by Comcast's speed. They end with the tagline, "Fast: It's Not For Everyone."