1) When three or more friends have a college lecture scheduled, and only one of them attends the class, that individual obtains the title "trooper."
2) An individual who, despite chronic marijuana usage, manages to maintain a high (no pun intended) level of achievement.
1) Guy 1: I'm skipping Pottery 105 today.
Guy 2: Yeah, I've got way too much to do, I'm out too.
Guy 3: I'm not skipping, it's fucking pottery.
(After Guy 3 leaves) Guy 1: He's a trooper.
2) Guy 1: So what'd you do after those blunts on Thursday?
Guy 2: Eh, I went to class, cleaned the house, did some homework, and got my taxes done.
In reference the Isuzu (or simply 'Zuzu) Trooper made between 1981 and 2002 (US market 1984). This car was one of the few true "SUV's" to have existed, ready to take on any off road conditions out of the box. Consider that most of the cars that you see on those National Geographic programs on safari in Africa are divided between the classic Toyota Landcruisers, Troopers and Land Rovers.
Sadly, with the downfall of Isuzu in the US it is unlikely that we will see any other Troopers, at least in true SUV form.