If your kid’s bag gets hot over the hours, this is the trick for you. Wet a sponge (a brand new one, please), put it inside a ziploc and then in the freezer over night. Fill the lunch box and put the sponge on the top. It will keep your kid’s food fresh.
Maybe you have a sippy cup at home. But if you don’t, or if you are visiting a friend, just ask for plastic wrap and seal the glass after filling it. Then make a hole with the straw and the rugs and furniture will be secure.