I don’t think it’s meant to be anything other than it is. I bet it was hers and he was holding it for her while she gave him head. It’s thirsty work and chocolate milk is a water equivalent for big gals.
Spilled milk in the car is nasty. Like urine, if you don’t get onto that bitch fast the subsequent smell is all sorts of wrong. If that was my car, the dude would be history, too.