I've often had left overs put in a styrofoam container to take with. The only problem is that the styrofoam containers are so big and bulky so I have to carry it instead of putting it in my backpack. That's why-ZIPLOC BAGS!-Never leave home (or hotel) without them. So I don't even ask for a container anymore, just pull out the ziploc bag, put my left overs in myself, and head on my way. That is, of course, unless the left-overs are something that need the firm container.