According to the chain, the yogurt in question will be Yoplait's Go-Gurt Low-Fat Strawberry Yogurt made exclusively for McDonald's.
The yogurt contains 50 calories and has 25 percent less sugar (6 grams) than the retail version of Go-Gurt, which has 9 grams of sugar per 2.25-oz serving. Basically, it's exclusive because it has less sugar than normal kid's yogurt.
The new yogurt option may be chosen in lieu of kid's size fries and/or apple slices.
McDonald's also has a new Happy Meal "ambassador" AKA mascot. He's Happy the Happy Meal... Have a look: