Mix sugar and cinnamon with a fork until thoroughly blended; set aside.
Slice bread into four 2-inch-thick slices. Cut each banana in half crosswise, then each piece lengthwise.
Place a bread slice flat on counter and tear out just enough from the middle (do not tear all the way through) to stuff two banana quarters side by side into it. Repeat with each slice of bread.
In a large pot or deep fryer, heat oil to 350 degrees F; use a candy thermometer to make certain oil does not get any hotter or the bread will burn.
Gently place one bread slice (banana side up) into oil for 1 minute or until light brown. Turn and fry for another minute. Remove bread from pot and toss in the sugar-cinnamon mixture. Repeat, using all ingredients. Cut slices in half just before serving. Makes 8 servings.