best boy
noun [ C ] theatre & film specialized uk/ˌbest ˈbɔɪ/ us/ˌbest ˈbɔɪ/
（拍电影或电视节目时）协助照明电工（负责铺设及维护电力设备的人）的器材助理
the person who helps the gaffer (= the person responsible for the electrical work) when a film or television programme is being made