Once found myself in a violent fight at an air base in Thailand and tried to use my aluminum 'cuffs like brass knuckles. Not enough "oomph" like you'd get with steel 'cuffs.
I won anyway.

Working detectives I picked a suit up at the cleaners and my aluminum 'cuffs were dangling from the hanger. Manager said, "I think you forgot something." Dang things were so light I left them in my coat pocket without realizing it.

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John