HAMBURGER:
It's thought to have come from the town of Hamburg, Germany. Here is where it's thought hamburger (originally called "hamburger steak") was "invented". The word hamburger first appeared in English in the late 1800's.
FRENCH FRY:
This goes back to President Thomas Jefferson. While he was Ambassador to France, he enjoyed a side dish there known as "french fried potatoes". When he returned to the U.S., he served them at Monticello. By the 1870's they had become a delicacy. By 1900 they were a common dish. The name was shortened to "french frieds" in the 1920's, then to "french fries" in the 1930's. By the 1960's, it was often common to just call them "fries".
HOT DOG:
The wiener was first introduced in the U.S. by Antoine Feuchtwanger, who was from Frankfurt, Germany. Some people called this small sausage "franks". Then, at the old Polo Grounds in New York City in 1901, a concessionaire began selling the "franks" by yelling - "Get your red hot(s) franks here!"
A sport cartoonist, T. A. Dorgan labeled them "hot dogs" by drawing the frank, or hot dog, as a dachshund dog on a bread roll.
SANDWICH:
It began with John Mantagu, the 4th Earl of Sandwich and British 1st Lord of the Admiralty, whose name first designated the islands of Hawaii. He was a compulsive gambler, who "invented" the sandwich by putting pieces of meat between two pieces of cut bread. He did this to allow more time to stay an the gambling table.