Apologies if this is in any way retarded, but I couldn't find a description of this online and I didn't get a chance to ask my instructor.
Anyway, last night I was turtling frantically following a deeply flawed armbar attempt, and my, larger, opponent was trying to put his hooks in. I couldn't buck him off or find his arm for the sweep, so in desperation I got my elbows inside his thighs and pushed myself backwards, eventually popping out between his legs.
Anyone else got this to work? Is it guaranteed to fail on non white belts? Is it totally common and I just haven't noticed?