I was leveling up a monk, and had a friend shuttle me to various battle pet areas so I can fast track my way to 90. For whatever reason, I was accidentally kicked off his Sandstone Drake some 300ft over Tanaris, and I instinctively pressed 'tild' key (On my warrior, I have 'tild' set to Heroic Leap, which is my movement key), which activated roll. I hit the ground while rolling, and instantly fell to 1% HP but survived, and got the Going Down? achievement.
I just had my friend test this again, and same result: falls some 100+ ft, roll right before ground, instant 99% health damage but survives.
This a glitch?