death grip

Short definition from Wiktionary

Noun

1. 1
   An extremely tight grip.
2. 2
   An extremely tight grip: The grip of something dead or dying.
3. 3
   An extremely tight grip: A grip that kills.
4. 4
   An extremely tight grip: A tight grip on the penis during masturbation.
5. 5
   A perilous situation or stalemate where failure or death is imminent.