So this inspired me to Google/Flickr search "chocolate milk" and see if anything interesting pops up. Here are some of the entertaining images I came across.
Not, very successful in the interesting design aspect, but I am always a fan of vintage package design. I have a few old magazines from the 50's and 60's and I love looking at and studying. Classically designed ads, old lingo, and a personality that is completely different than what you see now.