I doubt this is common, but the one and only time I've ever *blacked out* was the second I walked in the door to my house on a third plateau DXM trip. I open the door, glance inside, see my grandma and my mom lookin' at me, and that was it. She told me later that I fell face first on the floor. I never do Triple C's. The DXM I took was extracted into it's pure form from a generic cough syrup. Maybe I just freaked out and fainted. :P