Shifting while jumping from one block to a block that’s either higher / lower on the Y axis seems to trigger it, especially if you smash your head on the ceiling in the process. Paths also seem to glitch players out more than usual just by walking on them.

On a side note, if the plugin flags you for glitching, it tells you to shift and block with your sword, but uh… Blocking with a sword was removed back in 1.9.