The state of euphoria in which you more or less dictate a conversation. Usually achieved through some combination of a strong personality, an energized mood, respect and intrigue from your audience, and a string of successful jokes/valid points. In such a state, the people you're shmoozing with will tend to agree with most of the things you say, and laugh at even your mildly funny jokes. You also possess the power to dismiss topics or people you're uninterested in from the conversation, usually by either remaining silent or comically pointing out a flaw in reasoning or the unfunniness of a joke. In short, you are the alpha.
The person enjoying Conversational Supremacy: "Look at that dude who just ordered the chai and the muffin. Sporting not one but two fanny packs."
The friends around the table: *Raucous laughter
CS: "Talk about a panty peeler"
The friend that nobody likes: "Wouldn't it be so funny if we all wore those one day, but like as satchels or someth..."
CS: "Just stop. that's really stupid."
*laughter from the group
CS: "So who's up for a movie night?"
*animated response from the group