Though some of the greatest advertising slogans in history seem relatively simple ("Just Do It" is only three words, after all), most of the time, they're anything but. Here's how six of the most enduring taglines came to be.

1. “Just Do It.” The famous Nike slogan came from a rather unlikely source - spree killer Gary Gilmore, who received the death penalty for murdering two people in Utah in July, 1976. Just before a firing squad did their duty, Gilmore was asked if he had any last words. “Let’s do it,” he simply said. When Dan Wieden of Wieden+Kennedy was tapped to create a tagline for Nike a decade later, something about Gilmore’s words just seemed to fit. “Let’s” was changed to “Just” to add a dash of emphasis.

2. “Good to the Last Drop.”

Maxwell House has a pretty neat story for this one. They claim that while Teddy Roosevelt was visiting Andrew Jackson’s Hermitage in 1907, he insisted on taking a cup of coffee where Old Hickory once enjoyed his meals, saying, “I must have the privilege of saying that I have eaten at General Jackson's table.” As the story goes, after thoroughly enjoying his joe, Teddy smacked his lips and declared that the stuff was “good to the last drop.” Some years later, the coffee giant decided the slogan was a double win - it was a catchy phrase, but it also provided celebrity endorsement.

That being said, there’s a pretty good chance that the whole tale is just a pretty good bit of PR. The Theodore Roosevelt Association, however, claims they know of a credible witness who verified the whole conversation.

More from mental_floss writer Bill DeMain:

A few tidbits about Maxwell House – A Nashville Banner article from 1907 quoted Teddy Roosevelt as saying of that famous cup of coffee: “This is the kind of stuff I like to drink, by George, when I hunt bears.” Nothing about “good to the last drop.” Though maybe that phrase didn’t sound as quotable back then. Regardless, it was a big deal to have the president enjoying your brand of coffee, and in the days after Roosevelt’s visit, three different coffee companies in Nashville ran ads in the Banner claiming it was their java, not Maxwell House’s, that Teddy liked. Finally, though Maxwell House started using the “good to the last drop” slogan in print ads around 1917, they waited until long after Roosevelt was dead before they started using his name and image in their ads.

3. “A Diamond is Forever.” I wish I was one of those people who went to bed with a problem and woke up with the solution in my head. I’m not, but apparently copywriter Frances Gerety was, because she said the famous De Beers slogan came to her in a dream in 1947. It’s certainly enduring - the tagline has been a De Beers mainstay ever since. Advertising Age even named it the best slogan of the 20th century.

4. “We try harder.” This one is a rare moment of truth in advertising, according to Time magazine. When given the difficult task of making Avis seem appealing - Hertz had a firm lock on the top rental car spot in the U.S. - famed copywriter Bill Bernbach asked company president Robert Townsend why he thought anyone would use his company. “We try harder,” Townsend decided, and a slogan was born.

5. “I People weren’t exactly in a New York state of mind in 1977. Tourism was down, the city was getting a reputation for being dirty, and Deputy Commissioner of the NY State Department of Commerce William Doyle decided to do something about it. He requested a catchy ad campaign to boost tourism, and man, did he get one. Respected designer Milton Glaser created the iconic image thinking it would just be part of a quick, three-month campaign. He had no idea it would still be in use years later, even becoming a rallying cry after 9/11. The kicker: he did the work pro bono.

6. “That was Easy.” It would be nice if real life worked like the Staples ads: when you’re overwhelmed with work, chores, or life in general, all you have to do is push a button and some inventive and humorous solution magically appears to whisk your troubles away. Leslie Sims, a senior VP at advertising agency McCann Erickson, thought the same thing. Staples’ Easy button and “That was easy” line was... well, it wasn’t easy. It took a long time to come up with a concept that could quickly and handily show the abstract idea of “easy.”

I sense another post like this in my future - what slogans do you find intriguing?

