California Milk Processor Board's 'Got Milk?' Campaign, 1993. Thanks to the California Milk Processor Board's "Got Milk?" campaign, milk sales in California rose 7% in just one year. The impact ran across state borders, and to this day,you still can't escape the millions of "Got [Fill-in-the-Blank]?" parodies.
The advert didn't target people who weren't drinking milk, necessarily = it instead focused on the consumers who already were.
It's not always about attracting a new audience to use your product or services. Sometimes it's about getting your existing audience to appreciate and use your product more often.
Turn your audience and customers into advocates.