Let's just say right off the bat that companies generally do not have an official position on how to pluralize their brand names, because they do not want you to pluralize them at all. To protect their trademarks, companies need to keep them from becoming generic terms. They don't want people to use band-aids (generic), but Band-Aid brand adhesive bandages. They don't want people to eat oreos, but Oreo cookies.
But the pluralizing is going to happen anyway (even in the companies' own advertising campaigns). This is just how we talk about things. Nobody asks for adhesive bandages. Everybody eats Oreos. There are some brands, however, that people aren't quite sure how to talk about.
1. LEGO? LEGOS?
If you go to LEGOS.com, they don't just redirect you to LEGO.com, they first subtly scold you with a message that essentially says, "Oh, you must be looking for LEGO bricks and toys (not Legos, you idiot)." But that's toned way down from the message that greeted LEGO fans in 2005 (screenshot above via YesButNoButYes). It seems that only in North America do people talk about "playing with LEGOs" and "stepping on LEGOs." Elsewhere people play with LEGO, and step on LEGO bricks.
2. Lexuses? Lexi? Lexera?
Lexus, like Prius, also has a Latinate look to it that makes people hesitate at saying Lexuses.
3. Mercedeses? Mercedes?
Mercedeses doesn't exactly roll off the tongue. Some prefer to treat it like "moose" and let the same word stand for one Mercedes or four Mercedes. Or you could always say Benzes.
4. Kleenexes? Kleenices?
It works well as a mass noun—we talk about a box of Kleenex, but what if you want exactly three Kleenex brand tissues? It's an irresistible temptation to show off your familiarity with Latin "–ex" pluralization, is what it is.
5. Twix? Twixes? Twixen?
The first problem is that there are two pieces in a package of Twix brand candy bars. Are both of them taken together Twix or Twixes? And what if you have more than one package? Then you have two Twixes? Or two packs of Twixes? Or just a bunch of Twix?
6. Rolexes? Roleges? Rolices?
Are you trying to look like some kind of king with all your Rolexes? Then you may want to reference the Latin rex (king), plural reges, with Roleges, an appropriately pretentious and extravagant choice.
7. Filet-O-Fish? Filet-O-Fishes? Filets-O-Fish?
Fish is the plural of fish, unless you're talking different varieties of fish, in which case it's fishes. A Filet-O-Fish may actually be a Filet-O-(various)Fishes for all you know, so how to refer to more than one sandwich? You could take the easy way out with "Filet-O-Fish sandwiches," but isn't it more fun to go the attorneys-general route with Filets-O-Fish?
8. BlackBerrys? BlackBerries?
This one only concerns the written form. It just looks weird to have a y followed by a plural s, but pluralizing berry the usual way doesn't seem right either. I guess that's why "mobile devices" gained traction during the early BlackBerry days. Pretty sneaky way to do trademark enforcement, BlackBerry. Well played.
9. Priuses? Prii? Priora? Prien?
In 2011, Toyota ran an ad campaign where they encouraged people vote for their preferred plural form of Prius. Prii was the winner. But plain old English Priuses seems to be the more common choice in real life.
10. Google Glass? Google Glasses?
So far, people have been pretty good about following Google's trademark directive and calling it Google Glass rather than Google Glasses (I'm wearing my Google Glass today. Everyone is staring at my Google Glass). However, not that many people have one (them?) yet. We'll see what happens when more people start wandering through the house shouting "Honey, have you seen my Google Glass(es)?"
11. iPad2s? iPads 2?
There's a short period of time after a new version of an electronic product comes out when people want to refer specifically to that version. They don't just want to talk about iPads or iPhones, but about iPad2s or iPhone5s. Or iPads 2 and iPhones 5? Of course, "version 2 iPads" and "version 5 iPhones" would be the most prudent choices, but when you're into Lexera, Mercedeses, Roleges, and Filets-O-Fish, who really cares about prudence? I say iPad2zees and iPhone5zees.
All images courtesy of Getty Images