10-8

A common radio code in law enforcement, referring to a unit being available for a service.

As a slang term, it is also used to describe a person who was calm and suddenly became active.

Commonly written as "X8" (Roman numeral X=10)

"I will be 10-8 at 0600 hours."

"He was calm, but once I told him he was going to jail, he went 10-8 and started to fight."