I remember back in grade school and Junior High in the spring and fall occasionally making those tin foil TV dinners because the folks were both out in the field.   Never had a problem with them, just stuck them in the oven for 20 or 25 minutes.   Even now I have a $1 Banquet TV dinner, much to my wife's chagrin.    I always hear how unhealthy it is, but it does fill a hole in the stomach when you're hungry and in a big hurry.