When Jerad and I started living together I had really nice tupperware. The fancy heavy duty stuff with the nice lids that wouldn't leak no matter how much you threw them around. Those slowly managed to all disappear and we switched to the cheaper "gladware" type. Every few months (probably more like every month) I'd have to buy more because the boy can not bring tupperware home to save his life. Have you seen that commercial where the mom handcuffs the tupperware to her kid's arm so that he can't loose it? I totally got where she was coming from.
Eventually I gave up and we just started re-purposing containers. Used up all the yogurt? Wash the container and put it in the tupperware drawer. Empty jar of spaghetti sauce? Add it to the tupperware. It works out well. Our containers might not be cute, and they might not match, but we have all shapes and sizes and its not an issue if they don't always make it home.
The problem is on days like today when I'm running out the door and grab the container of sour cream to go with my lunch, only to open it at lunch time and find it filled with spanish rice. oops. At least I was having chili rellenos! The rice worked out perfectly as a side dish. I need to remind myself to check first:)