I trolled most tests in pretty much every High School course. I almost never knew when they were happening, and never prepared (of course, it's High School, nobody really needs to), and always got close to 100%, tending towards perfect. High School level essays are great too, because you essentially cannot fail, and I consistently could achieve top marks with the writing skills I developed while arguing with people on the internet in my younger years (lolwut).
But I have a friend who can claim far better than this. He has almost never payed attention in a course, in fact, he puts negative effort in to most portions of his life. When he is being taught something, he is actually doing other things the whole time, so he has shown up for almost every test he has ever written without even knowing what it was on, let alone how to DO the material. He passed Physics 11 and 12 by looking at the formula sheet 5 minutes before the test, asking me "So what am I actually looking for?", and then bullshitting the rest. He can answer questions correctly that he doesn't understand in the slightest through a combination of cross referencing, general knowledge, hazy recollection and guess and check. And he's dyslexic.
Basically High School is fucking hilarious.