People who refer to meat, fish, beans, etc (but they nearly always just mean meat or fish) as 'protein', as in 'I have salad and a protein for lunch' freak me right out
I have never heard this and would probably have to back away slowly if I did, blimey. 
As for the two slice definition of a sandwich, says who? What about the open sandwich? Or the clubhouse? Or a wrap? Or pitta? Also if you have a single slice and put stuff on and fold it then that is still a sandwich so really I think it has to include all food on bread. The oracle wiki agrees with me 
The modern concept of a sandwich using slices of bread as found within the West can arguably be traced to 18th-century Europe. However, the use of some kind of bread or bread-like substance to lie under (or under and over) some other food, or used to scoop up and enclose or wrap some other type of food, long predates the eighteenth century, and is found in numerous much older cultures worldwide.
The ancient Jewish sage Hillel the Elder is said to have wrapped meat from the Paschal lamb and bitter herbs in a soft matzah—flat, unleavened bread—during Passover in the manner of a modern wrap made with flatbread.[9] Flat breads of only slightly varying kinds have long been used to scoop or wrap small amounts of food en route from platter to mouth throughout Western Asia and northern Africa. From Morocco to Ethiopia to India, bread is baked in flat rounds, contrasting with the European loaf tradition.
During the Middle Ages in Europe, thick slabs of coarse and usually stale bread, called "trenchers", were used as plates.[10] After a meal, the food-soaked trencher was fed to a dog or to beggars at the tables of the wealthy, and eaten by diners in more modest circumstances. The immediate culinary precursor with a direct connection to the English sandwich was to be found in the Netherlands of the seventeenth century, where the naturalist John Ray observed[11][12] that in the taverns beef hung from the rafters "which they cut into thin slices and eat with bread and butter laying the slices upon the butter"— explanatory specifications that reveal the Dutch belegde broodje, open-faced sandwich, was as yet unfamiliar in England.