coffin corner

This is an aerodynamics term which refers to a narrow and critical altitude range where an aircraft’s stall speed approaches its maximum speed, which can lead to catastrophic instability.
This phrase is also used in American football to refer to the section of playing field, near the endzone, between the goal line and the 5 yard line in which punters attempt to pin the opposing team within, by executing a ‘coffin corner’ kick. This manuever is highly difficult and requires immense precision.