Any ideas on when this word originated? I did a search on Google and found several slang dictionaries with the word, but none gave a year. On the Simpsons archives site, a list of “yoinks” is given with the earliest episode being the fourth season’s “Duffless”. The episode is from 1993. Can anyone site an earlier use?
[pure speculation]
While I don’t know for certain, it certainly has the “feel” of a Don Martinism.
Even if it isn’t, it should be.
[/pure speculation]
[Bill & Ted]
All right, dude, as soon as we find out when Yoink is invented, we use the booth… we go back to just BEFORE it was invented, and we invent it, and get all the credit!
[/Bill & Ted]
Therefore, I invented Yoink, whenever I damn well want to. 
(In other words, even if it wasn’t invented by the Simpsons, it sure was popularized in modern culture by the Simpsons)
In the old “Scoobie Doo”'s, when they grabbed something quickly, there was a “yoink” type sound effect. Hanna-Bannana used pretty much the same SFX’s for all their cartoons, so the sound would be fairly embedded in the collective psyche of an entire generation. Saying “yoink” for the “yoink” type SFX would just be onomatopoetic usage.
Of course this is just my personal observation, and I’m guessing out my ass.
It coulda been just as easy “The Simpsons” invented “Yoink”.
(Bet you didn’t think you’d see “onomatopoetic usage” in type when you woke up this morning, did ya? Nah. I didn’t think so.)