I made a lot of jokes about it with my friends when I first heard about it, but it turns out it isn’t as random as it seems…
People have pointed out that in the scene where Anakin saves Jar Jar from Sebulba in TPM, Sebulba actually says something to Anakin in Huttese that sounds similar to ‘maclunkey’ (or ‘mac-a-lunkey’). Sebulba sounds like he is saying “Nik ma chawo, wamo, mokili macalunkey” which translate as the phrase “Next time we race, boy, it will be the end of you.”
Also, in 2008 The Clone Wars movie, there is a scene between Jabba the Hutt and Obi-Wan where Jabba says something like “Nichutu clunkey za beezka”, which translates to something like “either dead or alive”.
So, maybe ‘clunkey’ could relate to dead or death in Huttese, so ‘maclunkey’ could mean “this will be the death of you” or “this will be the end of you”. Obviously “maclunkey” meaning all of that makes that small word have an apparent loaded meaning, but Sebulba’s line seems to imply that “maclunkey” could just mean “This is your end.” Present tense, perhaps, rather than future tense, like ‘mokili’ could possibly relate to.
Do I think this change is totally unnecessary? Absolutely. Do I think it is more likely this all just coincidental gibberish? Highly probable. But it does make me wonder if Lucasfilm actually has some psuedo-vocabulary they use for simple Huttese when writing alien dialogue for the actors/voice actors to speak, and the variations are just due actors pronouncing words slightly different or loose translations.