Accomplished pilot. Loyal friend. Iconic hairy dude. Chewbacca is all of these things, but in Japanese, he's more. He's an "average moron". I say "Chewbacca", and you think, well, probably "Chewbacca". But in Japanese the name might involve different connotations.
Now, there are several theories about the origin of the Chewbacca moniker that range from chewing tobacco ("chew bacco" became "chew bacca") or that the name resembles the Hebrew word for scream or growl.
It's no secret that George Lucas drew heavily on Japanese films (and motifs) for Star Wars. Kurosawa's The Hidden Fortress was a huge influence in particular. Heck, Toshiro Mifune was apparently going to be Darth Vader.
On website Binary Bonsai, there is a fascinating rundown of Chewbacca's history. In George Lucas' original 1973 partial outline that would become Star Wars, there is a character named "Chuiee." Then, a character named "Chewbacca" appeared in a 1974 draft. Here's a description from the script: "The eight foot Chewbacca, who resembles a huge, grey bushbaby with fierce baboon-like fangs..."
In Japanese, "Chewbacca" is written as "Chuubakka" (チューバッカ), which sounds incredibly similar to "average idiot" (or "medium stupid", if you like!) in Japanese, which is "chuu baka" (中馬鹿 or 中バカ). Yes, "bakka" is different from "baka" (stupid), but they are similar enough so that when Japanese kids hear "Chewbacca" for the first time, they might make a joke about the character's intelligence.
A few years back, there was even reportedly a column in a Japanese magazine claiming that the name "Chewbacca" was derived from "average stupid" in Japanese — something that was mentioned in this Yahoo! Japan Q&A in which a net user wondered if Chewbacca really meant "average moron" in Japanese. (The answer was that, yes, there is a theory that says so, but George Lucas hasn't made the name's origin officially known.)
The caveat is that Japanese people really don't use the phrase "chuu baka" to refer to your average fool. Simply, "baka" (or "stupid"), or "aho" (アホ) for folks in Western Japan, suffice just fine!
However, there is Japanese for "ohbaka" (大馬鹿 or 大バカ), which means "complete idiot". And since "oh" (大) is used much like "large" for sizing, and "chuu" (中) is used for "medium" or "average", drawing a connection between Chewie and an regular dummy does make sense in Japanese, even if the term isn't widely used!
It's like someone who had a rough grasp of the Japanese language just put words together. Someone like George Lucas?