sorry, I gotta go take a fantastic means that you are troubled or bored or whatever and that consequently you want to leave. perhaps to think perhaps just to be alone without present company. an announcement of leave-taking without explanations.
see example above - as intro to the definition. i don't want to get technical or quibble about how you fill this thing out. i gotta take a fantastic.
by yogurt steele November 7, 2013