The question of whether it is good or right for Catholics to engage in raunchy humour seems to me to be one that eludes a simple answer. In some contexts and from some people, raunchy humour may be entirely appropriate and even virtuously motivated. When discussing the often sensitive topics of marital relations or family life, a certain amount of raunchiness can serve to alleviate bitterness or resentment by alluding to the often ridiculous and absurd elements of embodiment. There is something sublimely silly about immortal souls walking about united to flesh such that the flesh can and does fall short of the will, all of which makes cracking jokes about small boys and their preoccupation with their penises or grown women trying (and failing) to stay awake for a romantic interlude with a spouse both near-universal and extremely cathartic. Raunchy humour is earthy, embodied. When used to express something about the common experience of embodiment, it can be a good that draws persons together and teaches them perspective and tolerance towards their own physical nature and that of others.
Of course, like anything, raunch can be and often is misused. Raunchy humour can be directed at persons in an objectifying way, as many women have experienced. It can serve to cheapen or expose another by reducing them to their physicality and neglecting the value of the whole person.
It can also be used to intentionally cause offence to others, capitalising on differing cultural expectations and standards to create scandal for no purpose but to take malicious pleasure in causing scandal. There are many innocent things that shock or scandalise the tender of conscience, and while we are not abjured to cease to eat meat sacrificed to idols, we are abjured to avoid making a show of it around those who feel genuinely conscience-bound to avoid it. St. Paul (the original moral relativist, by some standards, it seems) cautioned the Corinthians not to embolden other believers to act in ways that they (mistakenly) believed to be sinful, for "since their conscience is weak, it is defiled" by following the example of those whose knowledge renders their conscience clear. "Those who think they know something do not yet know as they ought to know," says St. Paul, "But whoever loves God is known by God." So we are to "Be careful...that the exercise of your rights does not become a stumbling block to the weak."
Obviously, this is easier to apply when our audience is clear. If I am speaking within my house, I'll naturally guard against overt sexually-based humour around my children, since they lack the context for it and are not an appropriate audience. If I'm talking to someone I've just met, I won't make the same jokes I might with someone who knows me well. If I know my audience, I can choose words that will speak to that audience.
Online, however, audience can be hard to judge. There's often a difference between the intended audience, the potential reach of a piece of writing, and the actual readership. If I've found a particular audience who responds well to raunchy humour, and if my use of it is appropriate and person-affirming rather than objectifying, should the reality that my writing is accessible to a larger readership prevent me from writing with that particular subset in mind? Do I have an obligation to write for every person who clicks on a link or visits my page, when writing online?
My concern is that if every Catholic writer restricts themselves to the linguistic common denominator to try to write in a way that will communicate equally to every reader, we are likely to fail to communicate well to any audience. Conversely, if I fall into the habit of writing to please a handful of individual people already known to me, I may find myself falling into lazy habits, using shorthand labels and expressions and failing to explain my premises or qualify my statements, and effectively reaching a much smaller audience than I might hope for.
I don't, however, think I have a responsibility to write with every possible audience in mind. If a mode of writing can be appropriate and even virtuous within the context of a particular audience, as I've argued that raunchy humour can be, it remains appropriate even if others might see and misunderstand it. I am responsible to the person or people to whom I am speaking and to those who make an honest effort to understand me within the context in which I move and write. If I do become aware that someone has been scandalised because of differences in conscience, I should in charity both attempt to explain myself and encourage that person to follow their own conscience and not my example. I think the obligation to avoid scandalising others goes that far.
However, when potential readership extends to anyone with an internet connection, it no longer becomes clear which person is owed the greater care--the person who might experience my language to be a stumbling block, or the person who is in need of the communion and commonality that language could provide. To that end, the discernment of which audience to serve and reach out to is one that can only ever belong to the individual, in accord with his or her own understanding and conscience, and within the context of his or her own calling and journey.
So, here's the TL;DR summary, what I want you to take away from this:
Sometimes, you're not the audience. Sometimes, the audience is one that needs to hear embodied language appropriate to the ridiculous sublimity and sublime ridiculousness of embodied souls and ensouled bodies. Sometimes, the words that offend you are the instruments that edify and heal another. Sometimes, you need to consider that you might not be the audience, and that's OK, because God loves a lot of other not-you people too.
(For more, see my earlier two-part piece at the Personalist Project on the purpose of language.)
I'm adding this relevant quote here, so that I can find it again. From St. Josemaria Escriva:
What conversations! What vulgarity and what dirt! And you have to associate with them, in the office, in the university, in the operating-theatre..., in the world.
Ask them if they wouldn't mind stopping, and they laugh at you. Look annoyed, and they get worse. Leave them, and they continue.
This is the solution: first pray for them, and offer up some sacrifice; then face them like a man and make use of the 'strong language apostolate'. — The next time we meet I'll tell you — in a whisper — a few useful words.