Poolside nickname for the most common backstroke fault: you fold at the hip and your seat sinks away — as if you were swimming on an invisible chair.
The nickname describes exactly what happens: piked at the hip, you push a large braking surface ahead of you, and your kick points back and down instead of straight back. You work hard and barely move. The giveaways are a low seat and knees that break the surface. Where people go wrong is treating it as a leg problem and spending weeks fiddling with the kick: it is almost always triggered by the head lifting to look forward. So the fix starts at the top — back of the head in the water, waterline at your ears, head as still as if you were balancing a glass on it. Then press the chest a fraction downward and push the hips towards the surface; a pull buoy between the thighs makes the target feel obvious straight away. And correct only one thing per length — trying to fix everything at once makes you tense and creates new faults.