kiwi shampoo
A "kiwi shampoo" / "kiwi shampoos" is cop-slang for kicking a criminals' head in. Police have to wear shine-able shoes as part of their uniforms, and Kiwi is a popular brand of shoe polish, as well as being a popular scent for hair products . It was made more prominent by the TNT drama "Southland" using the term on several occasions.
The perp hit officer Valazquez in the head with the beer bottle he threw, so he decided to give him a good old Kiwi Shampoo before shoving him in the back of the patrol car.