fag end
noun
1- informal, chiefly Brit. a cigarette end〈非正式, 主英〉烟头, 烟蒂。
1.1
- an inferior and useless remnant of something劣质（或无用）残剩物：
the fag ends of cereal packets.
谷类食物包装袋里的残余物。
词源
early 17th cent. （in the sense 'remnant'）： from 15th-cent. fag 'a flap', of unknown origin. The current sense dates from the early 20th cent.