In a wider, more informal context, an allusion is a passing or casually short statement indicating broader meaning. It is an incidental mention of something, either directly or by implication, such as In the stock market he met his Waterloo..
The definition of a bump is a light jolt or a swollen, raised lump on the body. An example of a bump is the act of two toy cars hitting each other. An example of a bump is a welt on the hand. To bump is defined as to collide lightly. An example of to bump is for a car to knock gently into the back of another.
The bump bar is basically just a programmable keyboard. It mounts somewhere easy to reach so that the kitchen staff can use it to select the order on the kitchen display and then change the order state to ready or even selecting an item and marking it as ready.