(Note: cross-posting to this thread since it seems more appropriate here.)
I noticed this XKCD as well, and now that I think about it, I have the same question: what exactly
is the difference between ‘fell down a hole’ and ‘fell in a hole’?
Along similar lines, here’s another little conundrum which has been puzzling me for a while. English allows the directional ‘along’ to modify various verbs with non-directional meaning: ‘bubbled along’, ‘whirred along’ etc. Though non-directional directionals are practically a universal, this particular construction is a bit strange in several ways. For one, it is allowed only with a very particular set of verbs: ‘bled along’, for instance, is nonsensical. (Note that I am ignoring straightforward and extensions of the base meaning ‘follow a path’, as well as its comitative usage, as those are far less restricted.) More curious is its semantics; most sources I can find describe it as a progressive or continuous, but as a native speaker that doesn’t sound quite right, for it has an additional connotation of…
flippancy, almost? Except that I doubt that the ‘flippantive’ is a recognised grammatical category. I’d be very interested to know what the semantics of this construction are.