For me a booby-trapped sandwich sounds like one containing any of those ingredients your teeth don't easily cut through, meaning after you pull back from the first bite the whole slice of whatever threatens to come too, resulting in an extremely inelegant battle to chomp it off so you don't have it draped down your chin while you try to somehow pull it into your mouth like an otter with an eel.
BLTs are the worst for this: all three ingredients are candidates for not being quite bitten through.
BLTs are the worst for this: all three ingredients are candidates for not being quite bitten through.