"Backwards Long Jump". Referred to the glitch in Super Mario 64, where if you repeatedly long jump backwards up a slope / set of stairs, you will accelerate extremely fast—so fast that you break through walls, including invisible ones.
One of the most awesome glitches in the game.
Guy 1: Did you see that 0-star TAS that SwordlessLink and AKA made?
Guy 2: Yeah, the most awesome use of BLJ I've ever seen.