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In Heinlein's A stranger in a strange land, there is a moment when nurse Jill kisses Martian man named Mike and another man, Jubal, puts a comment on it. It comes as follows:

“Son,” he said, “you amaze me. I would have expected you to curl up in one of your faints.”

“I so did,” Mike answered seriously, without letting go, “on first kissing time.”

“Well! Congratulations, Jill. A.C., or D.C.?”

“Jubal, you’re a tease but I love you anyhow and refuse to let you get my goat. Mike got a little upset once—but no longer, as you can see.”

The only meaning of AC and DC I found was alternating current and direct current, but it is about electric power distribution and is definitely not my case. I have no idea about meaning and genesis of Jubal's mockery. Can anyone, please, explain it to me?

Don't pay attention to Mike's strange language - he is the Man from Mars and has a different native language and way of thinking.

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Are you sure you copied that all out quite right? “On first kissing time” is not what I would call English. – Janus Bahs Jacquet Aug 25 '14 at 11:21
Maybe it is just a play between AC/DC and A.D. (anno domini) and B.C. (before Christ)? – skymningen Aug 25 '14 at 11:21
Janus - your comment is weird (no offense!); the "on first-kissing time" phrase makes perfect sense. Note too he's a martian. – Joe Blow Aug 25 '14 at 11:35
skyminge - there's uttelry no connection to "before christ" - it's a common way to refer to sexual orientation. – Joe Blow Aug 25 '14 at 11:35
up vote 26 down vote accepted

In my youth (the 1960s and 1970s) AC/DC was a euphemism for bisexual. As far as I recall AC meant heterosexual and DC meant homosexual (derived from Alternating current and Direct current) and I suspect that Heinlein is using it in this way as the book dates from that period.

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@EdwinAshworth It's completely commonplace (today, 2014) to use "AC/DC" as a rowdy term to refer to the differences between homosexual and heterosexual. (Note that one of the top ten most famous rock bands of all times has this term as a name.) – Joe Blow Aug 25 '14 at 11:41
@JoeBlow the derivation surely is that Alternating current is about opposites (hence hetero) and Direct current is same to same, (hence homo), but I agree that the phrase is always used together as AC/DC, meaning swings both ways. – Purple Helen Aug 25 '14 at 12:10
JoeBlow, this is definitely dated at least in all parts of America I've been to (NYC, DC, LA). I'm active in the LGBT community and the only times I've ever heard this were in this book and The Talisman by Stephen King. I would not expect your average person to definitely understand it--maybe there's a generation gap? – thumbtackthief Aug 25 '14 at 13:50
It's archaic slang from the 50's and 60's. Still heard it some in the 70's, but hardly ever after that. – RBarryYoung Aug 25 '14 at 14:52
The trouble with the "heterosexual or homosexual" interpretation of "A.C. or D.C?" is that it makes no sense in the context of the passage. Jill is female, Mike is male; why would Jubal ask "straight or gay" in response to their kiss? – Russell Borogove Aug 25 '14 at 16:06

AC/DC refers to the two main types of electric power.

However, it's used humorously to mean "straight" versus "homosexual" sexual orientation.

It's that simple.

(Note that one of the world's most famous rock bands, is called "AC/DC" ... as well as referring to "electricity," as in electric instruments, it's a sexually-charged term.)

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perhaps someone could determine the origin of this usage or when it was first used this way. – Joe Blow Aug 25 '14 at 13:07
FWIW, the OED gives the following definition of AC/DC: AC/DC abbreviation. 1 Alternating current/direct current. 2 Bisexual. slang. Unfortunately it gives no date of first use (or derivation) for the slang version. – Purple Helen Aug 26 '14 at 14:35
However, I also found this on dictionary.com: AC/DC "bisexual," 1959, said to have been in use orally from c.1940, from electronics abbreviation of alternating current/direct current. Online Etymology Dictionary, © 2010 Douglas Harper (and elsewhere the idea that it means "accepts both types of current = both genders" which is rather neat) – Purple Helen Aug 26 '14 at 14:45

There is an old children's joke involving an electric eel who is asked by a friend how his date with another eel went. He responded that they weren't dating anymore because she was A/C and he was D/C.

When there is a strong romantic chemistry, we sometimes encounter another idiom that "sparks fly" upon the first kiss. This is also a reference to electricity. However, sometimes the couple find just as quickly that, after having gone that far, they simply aren't interested in pursuing the relationship any further; thus, incompatible.

Since alternating current and direct current are two forms of electricity that are incompatible despite being equally powerful, the metaphor of A/C vs D/C can express that idea fairly well. It does not require nor exclude a further meaning involving sexual orientation.

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Hello John. What we're really looking for (on this or any other Stack Exchange site) is a supported answer: one that you can support with authoritative references (in this case an encyclopedia, dictionary, or some other such document, showing this metaphorical usage). Edit your question and put in your support; then we'll be able to vote up your answer! [modified; after Matt Gutting] – Edwin Ashworth Aug 25 '14 at 19:16

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