APPLE COMPUTER
Question: Are you aware that "Think different" is bad grammar? You should say "Think differently"!
Answer: Although some might want "different" to perform as an adverb in this phrase, complete with an "ly" ending, Apple and its advertising agency intend it as a fanciful category, just as we might say "Think yellow," "Think change" or "Think playful."
Here's an illuminating quote from an interview with George Gribbin, legendary copy supervisor of the Young & Rubicam advertising agency and creator of the ungrammatical but highly successful slogan "Winston tastes good like a cigarette should":
"The American language is a good, salty, homespun, colorful language. And it is that way because of the vernacular. There's just nothing like pieces of the vernacular in advertising, or in any other kind of writing. It's not just using the vernacular, it's using the color of the life around you in a fresh way."
Think vernacular. Think different.