Many people will associate the use of the word fuck with the 1960s and 1970s, when it became one of the most common slang words for sex (a fuck), to have sex (to fuck), and as a general term of exasperation, surprise or anger (Oh, fuck! Fuck me! Fuck off/you!).
Various forms of the verb and noun are used in current English: fucked (cheated: as in, I was fucked by a conman); fucking (extremely: as in, fucking stupid); fucked up (messed up, or broken); fucking about (messing about).
The origins of the word are much disputed. In dialects of Norwegian and Swedish, the words fukka and fokka mean to copulate, suggesting a Scandinavian influence. However, it has also been suggested that it may be linked to the Middle English, German and Dutch words for to strike: fucken, ficken and fokken.
Clearly, the jury is still out!
Whether or not fuck was used in Victorian times, in the way Nan uses it, is not clear. It does not appear in the dictionary of Victorian sexual slang, and there has been some reticence about its inclusion in dictionaries; it did not, for example, appear in the Oxford English Dictionary until 1972.