Los Zetas is a criminal cartel operating in northern Mexico formed by former members of the Mexican Elite Forces.
Originally the members of Los Zetas deserted their Army ranks and went to work as the armed wing of a powerful drug trafficking organization known as the Gulf Cartel. In February of 2010 Los Zetas broke away from the Gulf Cartel to form their own criminal organization.
Zetas is used as a general synonym for a bad-ass organization .
“Watch it, man, or I’ll get the Zetas on your ass!”.