Well. You're on Hacker News. So I'm going to quote the Jargon File and then you'll stop complaining. Right, cobber?
> Further, note the prevalence of certain kinds of nonstandard plural
forms. Some of these go back quite a ways; the TMRC Dictionary includes
an entry which implies that the plural of `mouse' is {meeces}, and notes
that the defined plural of `caboose' is `cabeese'. This latter has
apparently been standard (or at least a standard joke) among railfans
(railroad enthusiasts) for many years.
> On a similarly Anglo-Saxon note, almost anything ending in `x' may form
plurals in `-xen' (see {VAXen} and {boxen} in the main text). Even
words ending in phonetic /k/ alone are sometimes treated this way; e.g.,
`soxen' for a bunch of socks. Other funny plurals are `frobbotzim' for
the plural of `frobbozz' (see {frobnitz}) and `Unices' and `Twenices'
(rather than `Unixes' and `Twenexes'; see {UNIX}, {TWENEX} in main
text). But note that `Unixen' and `Twenexen' are never used; it has
been suggested that this is because `-ix' and `-ex' are Latin singular
endings that attract a Latinate plural. Finally, it has been suggested
to general approval that the plural of `mongoose' ought to be
`polygoose'.
> The pattern here, as with other hackish grammatical quirks, is
generalization of an inflectional rule that in English is either an
import or a fossil (such as the Hebrew plural ending `-im', or the
Anglo-Saxon plural suffix `-en') to cases where it isn't normally
considered to apply.