Eww. I was flying out of Chicago one time and my crewmate and I were in the galley having breakfast after the service. As we were talking, she poured herself a cup of coffee and then opened a small, sealed carton of milk and began pouring it in when something suddenly dropped out of the carton into her cup. "What was that?!" I said. She gently poured out some of the coffee and took a spoon and sifted through the cup... coming up with a FOOT. We both inspected it... I think it was a rat's foot, but it looked almost like a chicken foot. In other words, a very large rat. Can't remember the name of the dairy, but it was catering out of Chicago O'Hare.
I immediately dumped the remainder of my granola and milk in the trash.