British slang for cigarette dates from the late 19th century and derives from a much older expression ‘fag-end’ that curiously enough is not slang and dates from the early 1600s. A fag-end was a perfectly respectable expression and described the last bit or poorest part of anything e.g. a rope or a piece of cloth and derives from the Middle English use of fag, which means to flag or droop. During the late 19th century, poor quality cigarettes would tend to droop even before they got to the fag-end. Subsequently, all cigarettes became known as fags. Fag meaning a tiresome chore dates from the late 18th century as does the public school fag who performed such chores. Fag is also American slang for a homosexual, dates from around 1920 and is an abbreviation of faggot, which means the same thing.