The first independent Diet Pepsi campaign, "Girlwatchers," focuses on the cosmetic benefits of the low-calorie cola. The "Girlwatchers" musical theme becomes a Top 40 hit. Advertising for another new product, Mountain Dew, a regional brand acquired in 1964, airs for the first time, built around the instantly recognizable tag line, "Ya-Hoo, Mountain Dew!"