Chacor wrote:So, anyone have any good theories why "Your Dad" just doesn't fly?
Possibly because matrilineal relationships are easier to trace, and more likely to apply to, and insult, a wide base of opponents. Anyway, people who trace the contest to the older "Dozens" insult competition might find that plausible, especially for more transparently insulting instances. I, personally, think there's a bit more to it.
First, consider that "Your MOM [something or other]" is one of certain phrases almost garunteed to have risque implications, whatever it is that she did. Another example would be "I'd [verb] her [noun] any time she wants." It works for even such mundane things as carrying groceries, an activity which I find it hard to put *any* subtext to in real life. The suggestion, then, seems to be purely in the grammatical structure of the statement itself.
Traditionally, and I seem to recall there's good evidence this game has roots so far back that Tradition Was Law, women are considered more passive, especially in ::ahem:: certain regards. We also tend to speak in active phrases rather than passive ones, or so my English teachers through the years would have me believe, so there could be the added element of a comedic inversion in which "your mom" is behaving somehow uncharacteristically "aggressive" simply because the emphasis is placed on her being one who acts. Continuing, this has a variety of implications about her personality, ranging from derogatory to titilating. ("You [action(ed)]." "Yeah, well, your MOM [action(ed), possibly last night, by implication with myself].) So, we're led to believe, your mom is somehow less than ladylike, and the speaker is reaping all the benefits.
The "that's what she said" bit is, in some instances, almost the exact opposite, implying that she is *reacting* to something just as the person being quipped at has reacted to a recent turn in conversation, thus placing that speaker in a passive role.
If that seems a bit of a stretch, consider that the other, more explicit implementation of "that's what she said" usually implies a specific deficiency, which the titular "she" is forced to suggest a means to overcome. ("Maybe you ought to [proposed solution]." "That's what she said.") Still an implied passivity, and what humor seems to have been inherent in the joke before it became sheerly ridiculous comes again from inverting that assumption. An inversion very nearly complementary to "your mom," if my theory is to be believed.
I dredge all this up since, in my experience, the two phrases are almost always linked. Bring up one, and the others is *much* more likely to follow, and the usage of "that's what she said" has a fairly strong influence on what "your mom" did. It could be only because both are largely defanged, mildly sexual insults, and thus "edgy" enough to add a nervous overtone to a simple joking insult. Even given that possibility, it's clear to me that both of the usual implications of "what she said" are highly suggestive with regard to "your mom's" popularity and the relative scarcity of "your dad."
"... for a man to understand what he himself says is one thing, and to understand himself in what is said is something else." -Soren K.
An ironic motto of sorts:
The ability to quote is a serviceable substitute for wit. -W. Somerset Maugham.