Are You Smarter Than a Sippy Cup?

I've outsmarted the sippy cups. 

Cheeky little devils; randomly disappearing and reappearing day in and day out. I'd fill them with milk (red for the fiesty kid, pink for the princess, green for the soccer nut–I had the color coding down to a science) and after the kids would mess with them for a minute and toss them on the floor, I'd put them in the refridgerator. But when I'd go back half of them would be missing. Gone! I'd get new ones. Pretty soon there were twelve cups in my fridge and only half of them could I figure out belonged to who.

At the end of the day, I'd dump all the unused milk into a bowl for the neighborhood "stray" cat and put the cups in the dishwasher. And the next morning, lo and behold, there they were, every darn sippy cup I'd been looking for, clean and dry in the top rack. 

Turns out that some sippy cups are chameleon–they change color, depending on how hot or cold they are! In the fridge, princess pink becomes eggplant. And how do you assign eggplant?