Surely you're choking!

In Shabbat 67a:

כי האי תנא תני תנא בפרק אמוראי קמיה דר' חייא בר אבין א"ל כולהו אית בהו משום דרכי האמורי לבר מהני מי שיש לו עצם בגרונו מביא מאותו המין ומניח ליה על קדקדו ולימא הכי חד חד נחית בלע בלע נחית חד חד אין בו משום דרכי האמורי לאדרא לימא הכי ננעצתא כמחט ננעלתא כתריס שייא שייא

or in Soncino's translation:

A tanna recited the chapter of Amorite practices before R. Hiyya b. Abin. Said he to him: All these are forbidden as Amorite practices, save the following: If one has a bone in his throat, he may bring of that kind, place it on his head, and say thus: 'One by one go down, swallow, go down one by one': this is not considered the ways of the Amorite. For a fish bone he should say thus: 'Thou art stuck in like a pin, thou art locked up as [within] a cuirass; go down, go down.'

The chapter of Amorite practices are the superstitious practices forbidden as such in the 7th and 8th perek of Tosefta Shabbos. And it is not really clear to me why this should not be a superstitious practice. It is quite possible it is because it works, and so it is not superstitious but rather real. (Compare to the dispute regarding the treatment for a bite from a rabid dog.) And what is means that it works is either that Rabbi Chiya bar Avin believed in it, such that it wasn't superstitious, or that they tried it out and it actually worked. Or, for example, one could posit that this is a special incantation created by Chazal using forces of good, and so is not superstitious. Or that it was based on some system which works, or in which they believed, such that it was not classified as superstitious. Or finally, that Rabbi Chiya bar Avin had some (superstitious) teacher who taught to do this, and so of course it could not be superstitious.

Regardless, I would not personally do this, for I feel that it is superstitious, even if it is not technically darkei Emori.

Avakesh has a post about this incantation, where a doctor (!) proscribes this for a rav, and some questions and answers with Rav Belsky. In terms of the latter:

Additional Note 2: We asked HaRav Yisroel Belsky, Shlita, some questions
regarding use of the Lachash.
Q. Would it work with any food upon which one is choking--and not only on a
bone, as seems to be evident from the previous story which involved a vegetable?
A. Yes. It works with any food.

Q: If one did not have more of that food--could he place something else on the
head? Yes, he could place the empty plate from which the food came.

Q: Did the person choking have to recite the Lachash—or could it be another?
It could be someone else close by. In fact, Rav Belsky related that he was at a
small seudah at which one of the participants began to choke, and he (Rav
Belsky) immediately put an empty plate on the choking person’s skull, and said
the Lachash. The food immediately dislodged with no pain. This was, of course,
the talk of the balance of the seudah--a miracle in front of their eyes!
Incredibly, about a year later, Rav Belsky attended a similar seudah with the
same attendees--and someone began choking again. Rav Belsky once again took
action with the Lachash, and the food dislodged, although the person choking
this time experienced discomfort afterwards for about ten seconds. After this
life-saving event, the people only seemed to discuss that this time there was
pain for several second afterwards... They were already used to the miracle
from last year!

I remember hearing a talk a while back by Rav Belsky. He is very machmir about things being darkei Emori, and coming from pagan or superstitious roots. Such that, for example, he condemns homeopathy for coming from Eastern religions, and therefore declares it forbidden. (From what I think is greater exposure to this, I think that he had been misinformed about this.) But then, immediately after declaring a whole range of alternative treatments forbidden, he gave the same two stories as above. I have a sneaking suspicion that, given the advance in the understanding of medicine, while it might not have been darkei Emori for Chazal, it might absolutely be darkei Emori when modern Jews, including Rav Belsky, perform it!

And perhaps the seforim hakedoshim have these extensions, to non-bones, to empty plates, and to other people saying it. But otherwise (and perhaps even if), it strikes me that this is overreach past the strict letter of the law which R' Chiyya bar Avin permitted. And that this is the feature creep which happens in superstitious practices which just work, rather than which work based on some existing system which we happen to understand.

Yet we have instances in which it dislodged! How can I deny the efficacy of this lachash?

Well, I have two answers. One is that, when people are choking, they try clearing their throat. And for some number of people, it will work. At the same time, if someone tries to perform this trick, then they will interpret the cleared throat as a result of their own efforts at incantation.

The second is that, as a rationalist and amateur linguist, I can readily explain just how this would work. Because of the placebo effect, the person doing this or having this performed on him will think it will work, and may relax a bit. Perhaps this would aid in getting the bone or foodstuff unstuck.

Furthermore, by holding the same food over his head, he stretches his pipes in a certain way. Then, consider the "incantation": חד חד נחית בלע בלע נחית חד חד . We don't necessarily realize it, because we Ashkenazim pronounce our chets like chafs and our ayins like alephs (or rather, like nothing at all). But ayin and chet, as the Amoraim pronounced them, are actually gutturals. And every single one of the words in this incantation has on of these difficult gutturals in it. Combine it with the other phonemes, and you are giving yourself quite a linguistic workout. Do this when you have a stuck bone in your throat, and it certainly makes sense that you could dislodge a bone!

Of course, as Rav Belsky practices it, he puts an empty plate on someone else's head, and he pronounces the incantation himself. My rational explanation would not account for the efficacy of that. But that admittedly doesn't bother me all that much.