I think there must be a language difference between us, since I usually interpret "for the lulz" as meaning "without a [good] reason." Kudos to you for doing well on it.
The oddest reason I've ever heard for taking a standardized test was from a fellow who was an SAT tutor. He would take the test in order to covertly write down good math questions onto his calculator while the instructors weren't looking. He made a point of telling me that when you do this, you have to make sure you answer most questions incorrectly. He knew other tutors who took the tests, got perfect scores, and then were told they couldn't take it again. There was almost pride in his voice when he said to me (paraphrased), "If CollegeBoard sees a 30-year-old man acing the SAT, they're going to look at him funny if he tries to take it again. If they see a 30-year-old man bombing the SAT repeatedly, they're just going to think he's stupid."
Doing this is of course morally dubious, to put it nicely. But I still am amused by the whole thing. There's a degree of "sticking it to the man" both in pilfering question examples from CollegeBoard and lowering the curve by an infinitesimally small amount when he takes the exams.
That was actually a smart idea to fail the exam. As a SAT tutor your first instinct would be to show off and try to get a perfect score.
To add another anecdote, I know many people who have been through the prison system. Certain prisons will give you a test on entry to see where your skill level is on the 3 Rs. The firm rule is FAIL THE TEST. Do not try to be smart. The dumbest ones get the priority for school places in the prison. Schooling = extra credits = early release from custody.
There must have been some use in taking it for you, right?
Otherwise, I guess I am missing the joke.