It's basically their Oreo Cookie Ice Cream Shake plus peppermint syrup to give it a cool, minty flavor and pink color.
The shake was first introduce around this same time last year. The suggested price is $2.79 for a regular 16-oz shake and $3.29 for a large 24-oz shake (may vary).
Nutritional Info - Jack in the Box Peppermint Oreo Shake - Regular (16 fl oz)
Calories - 881 (from Fat - 403)
Fat - 45g (Saturated Fat - 30g)
Sodium - 367mg
Carbs - 111g (Sugar - 89g)
Protein - 12g