Affixes are normally added to the start or end of a word, where they’re called prefixes and suffixes, respectively. But sometimes they appear in the middle, as infixes. (There are several other categories of affix.)
Infixation in English is often jocular or playful, as in “Homer-ic” edumacation, or Ned-Flandersy scrum-diddly-umptious, where diddly is infixed and um is reduplicated. (If you’re unfamiliar with reduplication, you might want to click that link for a summary: it’s relevant to what follows.)
Another familiar form of infixation is expletive infixation, as in absofuckinglutely, where the infix serves to intensify the expression. Less rude is absobloodylutely, and milder still but retaining the structure is absoposilutely, which borrows posi from positively.
Song Kang-ho in Thirst (2009)
I didn’t expect to see absoposilutely in the subtitles of a Korean horror film, but there it was. It seems unlikely that it was used as a straightforward synonym for absolutely. It made me wonder whether Korean has an analogous system of emphatic infixation, or what kind of morphological construction the translation might have served to suggest.
I know very little about the Korean language, but I found an interesting paper, Hyung-Soo Kim’s “A new look at partial reduplication in Korean” (PDF), that discusses “the problem of having to accept infixation only in partial reduplication in Korean because there is no evidence for infixation elsewhere in Korean morphology.”
So a partial answer to my question is that Korean doesn’t appear to have infixation,* but it does have internal partial reduplication, an instance of which may have been what was translated into absoposilutely in the film subtitles. But that last part’s a guess.
For more on the use and variety of affixes, see my post “Morphogasmic affixation” and the links therein. You might also enjoy John J. McCarthy’s “Prosodic structure and expletive infixation” (PDF), which characterises expletive infixes according to metric phonology – that is, it offers an explanation for why we tend to say absofuckinglutely rather than abfuckingsolutely or absolutefuckingly. If we say it at all.
* Other sources I looked at include Jongho Jun, “Variable affix position in Korean partial reduplication” (PDF); Alan C. L. Yu, “A Natural History of Infixation” (PDF); and a few items on Google Books. [Edit: I removed a quote from Hyung-Soo Kim’s paper because it didn't really serve the purposes of this post.]