a response to someone's statement when they show authority, dominance or certainty in the statement. If they put some emphasis on their statement and want everyone to know that they run the show, you respond with the phrase. It has a sarcastic tone and can abruptly end the conversation at times.
a sarcastice phrase directed toward complete idiots. If an idiot makes a comment, an appropriate response can be a 5 second stare followed by a very loud, sarcastic usage of the phrase. This gets the point across and will usually leave the idiot speechless.
Idiot: I ran 5 miles with JIINSEENNN COOOAAACHHH today!