Copying a manager (one's own or the target's or both) to add a threatening aspect to an email. The threat is often implied as this strategy is employed after some correspondence has occurred without management visibility so as to goad the target into complying. It can, though, be used at the outset as a preemptive strike.
email copied to management as above
verb: I can't go out tonight, my coworker mcc'd my boss, so I'll have to stay late to finish the project
noun: I'm going to ignore that mcc because the VP is on my side.