Man, I used to be one of those people who said just eat before you fly and stop being cheap about it. Then I got stuck at O'Hare with a four hour delay and paid $19 for a soggy wrap that tasted like wet cardboard, and I totally changed my mind. The foil is the whole problem here, not the food itself, because that shiny stuff lights up the scanner like a flare and the agents have to look at it. Wrap your sandwich in plastic wrap or a plain ziplock bag instead and it slides right through without anyone batting an eye. Also put it in your carry on and not a checked bag, since cold sandwiches keep fine for a few hours anyway. Bring a soft one like a PB&J or a bagel too, because anything squishy survives the trip better than ham and cheese does.

My old boss called that shelf the attic of the chimney.