from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Football Either corner of the field formed by the sideline and the defending team's goal line. The ball may be deliberately punted out of bounds in this area, thus forcing the receiving team to play very close to its goal line.
Sorry, no etymologies found.
You don't stay within that forty-knots-per-hour margin, you turn the coffin corner and you've had it.