In Oni, the "Hugh Jass Truckin' Lines" label can be seen on both doors of both armored trucks you see: interestingly, in the first and last chapters.
I'm not sure if the Hugh Jass credited in Special Thanks is a 100% gag name as it usually is (i.e. it doesn't correspond to a real-life person or group).
There is a rock band called Hugh Jass (http://www.hughjassrocks.net), and possibly other perfectly real people that chose to go by this gag name.
So maybe the credits and the marking on the trucks refer to someone or something real that more or less directly participated in Oni's development.
Another gag name in Oni is BGI. On the original Oni Central Forum, the developers admitted that it was just standing for Bad Guys International
Other easter eggs in Oni include more or less obvious references Myth and Marathon, "Bungie numbers" and names of Bungie employees (three on a poster, two others in terminals, maybe more).
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