McDonald’s broke a grammar rule with its 2003 jingle, “I’m lovin’ it.” (Bonus points – it’s also grammatically incorrect because loving isn’t a conjugated form of the verb love – it’s a tense. Specifically, progressive tense.)

Even though this jingle is slang and grammatically incorrect, it’s still McDonald’s most successful ad campaign. McDonald’s only spent $1.37 billion on advertising in 2003. In the first quarter of 2004 alone, their revenue increased by $455 million.

Now that’s a catchy jingle to the tune of dolla dolla bills. But a lot of business owners won’t use slang.

What to tell your clients: Brands are in the market to do business not to teach grammar.

Copywriting’s job is to connect with readers. To do this, you have to write in the same language. You have to use words and phrases your readers use.

Ask yourself, would slang be appropriate and entertaining to your audience? Does your audience use slang?

If your answer is yes, then break this rule. And make mad cheddar off that ad.