I've noticed something about the informal terms we use for sex, specifically the verbs, and more specifically the way we divide them into the dirty ones and the ones you can say in front of your mother. I'm not a linguist, so I'm not even sure if there is a technical distinction between these two kinds of verbs1, but I've noticed that the polite and formal terms generally require a preposition, but the naughty or informal ones do not. Let me illustrate with two examples:
Polite:
"Last night we went to dinner, and later I had sex with her."
Impolite:
"Last night we went to dinner, and later I fucked her."
In the first sentence, 'with' is the preposition in the prepositional phrase 'with her'. The second sentence lacks a prepositional phrase. The two sentences convey the exact same information, but are constructed in different ways, and this might just be the key to the polite/naughty slang division. This difference can be seen in almost all of the verbs we use to describe the horizontal bop. I list a few below, to show my point.
Polite/nice:
Impolite/dirty/colloquial/uncouth:
- To fuck
- To shag
- To screw
- To bone
- To bang
- To bugger
- To hit-and-quit
- To surf-and-turf
To illustrate this further, to say "I sexed her" (people really say this!) is more vulgar than "I had sex with her", though the differences in the phrases do not explicitly change their meaning. My theory is that it is not so much prepositions in general, but the 'with' that makes all the difference. 'With' implies a reciprocity in the act; that is, that both people are participating in it. This is why 'to go down on' is a rude expression. One can shag a tree just as much as one can shag a person, but one cannot truly have intercourse with it. To do unforgivable things to someone is bad, but to do unforgivable things with someone probably means you're both in on it.
This isn't an iron-clad theory, and there are certainly exceptions. "To bump uglies with" and "to make animal sounds with" could be considered improper ways to describe the act, and terms like "to make love to" and "to do" really couldn't. The first two just conjure up images that make them offensive to some, and the second two have been overused to the point of acceptance into acceptable language. Also, using 'fuck' in any way, even if it being followed by a 'with', is always rude, so that's another one that isn't explained by this idea, but I think that the general theory still stands in most cases. If the term implies co-operation of some kind, generally by using the preposition 'with', it is more acceptable in conversations with the great aunts than an equivalent term that implies one-sided action upon one person by another.
All this might also be a contributing factor in the way "talking dirty" works. I seriously doubt that anyone is more turned on by hearing "yeah, I'm gonna have sex with you now" than by "yeah, I'm gonna fuck you now". The lack of a 'with' gives the sentence a kind of dominant-submissive air, which is one of the main functions of dirty-talk (or so I gather). Similarly, the taboo that is present in the implication of non-consensuality is probably also a factor, and the presence of this implication in the past has given us a perception of these terms as being innately 'naughty', adding to the effect. That it is generally considered unacceptable to say these words in public might also add a sense of intimacy to their utterance, as if it is a secret to be kept from others.
This is all entirely speculative and unscientific, but I think it is something to think about, since language can influence thought as much as thought influences language.
1 - Some messages from C-Dawg have shed some light on this distinction, and here I've moved them around a little so that they make a paragraph:
The distinction seems to be between transitive and intransitive verbs. "We fucked." is intransitive, "I fucked her" and "we fucked each other." are transitive. The object acted upon by a transitive verb is the difference between the two, but while the "her" in "I slept with her" might pragmatically be an object acted upon, grammatically it is not. That still keeps the idea of the "shared" experience being the difference between polite and impolite. It may be that "fuck" has become impolite because of its frequent usage in the transitive sentence (which contributes to a "sex object" mentality), but "and later we fucked" or "and later we fucked together" should fall into the polite category.