One of the most (in)famous verboten everyday topics of the Victorians was, of course, sex and sexuality, and the prohibition of discussion of those topics in public. This is something that holds true to the stereotypical 'victorian' imagery. I want to be very clear, however, and notes that this does not mean that Victorians themselves were prudes or particularly hypocritical about sex and sexuality. Those ideas and caricatures (hypocrisy, prudery, etc) are caricatures created by the later victorians (1870s+) of their parents, the early Victorians (early 1800s). The most famous of these, and indeed, probably the work that did more to create the idea of the 'Victorian' is Samuel Butler's Way of All Flesh, which is a semi-autobiographical inveighment against his own parents. '

Indeed, with all of the problems and critiques of Foucault, he is definitely right when he remarked that the nineteenth and twentieth centuries are more united than divided by their great interest in sex and sexuality, something that doesn't feature as much of a concern, I would argue, in earlier centuries. Michael Mason notes that

It is correct to think that the later twentieth century, in the West, is unusual in its permissiveness about sex. By the same token, it is wrong to single out the Victorians as exponents of the opposite philosophy...Attacks on masturbation may seem absurd to twentieth-century Western readers, but we cannot take heard from the notion that only the demented Victorians thought otherwise; our culture is hopelessly outvoted on this question as on many others relating to human sexuality. Male and female masturbation, unconstrained liaisons for both sexes and all kinds of non-marital intercourse for women...[etc etc] have been deplored, repressed, and even punished in the majority of known human societies.

Mason goes on to argue that much of our stereotypes of Victorians as Victorians originate from their own reactions to eighteenth-century developments that tend to strike us as very progressive and positive, but to them were seen as negative. I am frequently reminded of Lawrence Stone's famous idea of 'the pendulum' in Family, Sex and Marriage in England:

Historical change is not a one-way street, and even in the West over the last five hundred years, continuous linear development has only occurred in the one field of technology. The trend towards the isolated nuclear family, greater personal autonomy, and emphasis on affective ties has not run a steady course from the sixteenth century to the twentieth. In terms of both sexual attitudes and power relationships, one can dimly begin to discern huge, mysterious, secular swings from repression to permissiveness and back again.

So yes, you would be frowned upon very strongly by the Victorians by trying to discuss sex and sexuality. Indeed, when one such person tried to do that in The Maiden Tribute of Modern Babylon he was roundly denounced for bringing pornography before the eyes of the public--even though he was trying for an expose on child prostitution. I will let /u/prehensilefoot elaborate a bit more here.