is there a translator in the house?

"Step 6. Carefully prise the rubber bung from position between the main jet housings and unscrew the pilot jet, which is located below the bung. The needle jet and main nozzle, which lie in the main jet housings, can be removed by pushing them out from the venturi side of the carburettor, using a finger or a suitable piece of wood which will not damage the brass."

I understand that I can use my finger or a suitable piece of wood but what and where is the "bung?"