Mutant 'dirty' word

[Douglas G. Wilson]

Recently I ran across (in a piece of modern Japanese, uh, literature) the
word "imarachio" (written in katakana): the context suggested that this
denoted a sex act. Of course Japanese "ferachio" = "fellatio" is quite
common (often abbreviated "fera"), and virtually any English-language word
related to sex is common in Japanese, judging from the Web. But what is
"imarachio"? Could it be "irrumatio"?

Casual Google using katakana indicates that it is indeed "irrumatio". But
"irrumatio" should be "irumachio" in Japanese, shouldn't it? Or possibly
"irumate[i]o" with subscripted "i" kana?

Well, the approximate 'raw' Google numbers are:

"irumachio" [katakana] 200
"iramachio" [katakana] 14,700
"imarachio" [katakana] 7,700
"iramate[i]o" [katakana] 400

For comparison, in Latin alphabet (obviously sampling a much larger segment
of the Web):

"irrumatio" 900
"irrumation" 1,200

Quick glance at a few Japanese-language sites (including Wikipedia)
indicates that the sense is the same as in English, more or less,
"irrumatio" indicating a greater degree of vigor on the part of the
irrumator (or fellatee) by comparison with "fellatio".

There are two linguistic questions here: (1) why "iramachio" (usually)
instead of "irumachio"; (2) why "imarachio" (often) instead of "iramachio".

Perhaps some of the scholars who are expert in Japanese can enlighten me.
Meanwhile, here are my sophomoric ruminations.

It is likely that "irrumatio" was adopted proximately from English and
probably largely from written English, so perhaps the notion was that the
second vowel would be that in the English word "rum", giving "iramachio".

The mutation to "imarachio" is peculiar. My callow speculation: the
activity is a form of fellatio ("ferachio") so its name should end in
"-rachio". I wonder whether there is influence from Japanese "ima" = "now",
i.e., "ima" + "[fe]rachio" = "now-[fe]llatio", an 'urgent' form of fellatio.

Perhaps somewhere among those thousands of Japanese Web-sites these
questions are answered. Am I missing something?

"Irrumatio" was of course introduced on this list last year.

-- Doug Wilson