I'm going to use this post as a running list of examples of over-latinate plurals.
Almost everyone is familiar with the uncertainty surrounding the plural words like platypus, octopus, and syllabus. They look kind of Latin, and a lot of high profile words with this kind of shape form their ending by changing the last syllable to "i" (alumni, foci, fungi). But in these uncertain cases, prescriptivists tell us we are hypercorrecting, and engaging in pseudo-Latin.
But, I'm not so sure if this is simply a case where people are well educated enough to know the -us → -i, rule, but not enough to know a Greek word when they see it. For instance, I've seen it overapplied to words which aren't even spelled -us. At 1:10 in this video, John Stewart says
"We cannot allow ourselves, to get complacent, for the face of tyranny has many... orifi."
Ok, clearly this was done for comedic effect, but I think it's only funny because we recognize "orifi" as well formed, but prescriptively incorrect.
Even stranger, I recently had an experience where I wasn't quite sure how to form the plural of danish (as in pastry). I was telling a dinner party that I wasn't very hungry because I'd eaten a few at a coffee shop earlier. I said "I had a few..." and paused, because the first thing that came to my mind was "dani". Even stranger, my sister, who had seen me eat the offending pastries, offered "Dani?" And we are not alone! check out this Yahoo! Question.
Whats the plural for danish? Like if you have two danish(es?) is it dani? Or just danishes?So for some people, the semi-productive latinate plural rule doesn't care if it's dealing with s or sh.
In some ways, it makes total sense. I'd argue that the the sequence [ɨsɨs] isn't the greatest one in the world. Once you've got a rule which would let you avoid it, why not use that all the time?
In a note related to irregular plurals, I was once asked in a question period about what kind of "metrices" I use. This is way more interesting than it initially seems. "Oh, that's just analogy from matrix," you say, but it isn't quite. The singular form is just metric. The word doesn't have the appropriate shape to undergo the irregular pluralization until after you've already added the regular plural suffix! So you wind up with metric → metrics → metrices.
UPDATE: December 7, 2011
Hilary Prichard has pointed me to this (rather depressing) example from Donald Trump, discussing his plans on creating a version of the Apprentice for children
“We’re going to be picking 10 young wonderful children, and we’re going to make them apprenti,” Trump said. “We’re going to have a little fun with it.”
UPDATE: December 8, 2011
Jon Stevens pointed me to this segment of Anderson Cooper's show called the RidicuList (originally broadcast December 7, 2011). At 2:35, Cooper says
I did this story three different times six months ago on the RidicuList, and some of the video from the Colbert Report that-- Some of the video they used, came from the Third Eagle's video responses to my RidicuLists. I like to call them Ridiculi, but you get the point.