Cowboy diplomacy

From Memory Alpha, the free Star Trek reference.

The term cowboy diplomacy is used by Jean-Luc Picard to criticize Spock's unauthorized participation in the Romulan underground movement. Picard claimed that Spock's attempt to foster the peaceful reunification of Vulcan and Romulus was an action that had significant consequences to the Federation, and thus the Federation Council should have been consulted first. (TNG: "Unification I")

This term is later used by Stefan DeSeve as a code word given to him by Spock, in order to prove to Picard that his request to move the Enterprise to the Kaleb sector was legitimate. (TNG: "Face of the Enemy")