Sarcasm is known as "the activity of saying or writing the opposite of what you mean, or of speaking in a way intended to make someone else feel stupid or show them that you are angry" (Macmillan, 2007).
if one pair of w 1 and w 2 satisfies our rules among all combination of w 1 and w 2 in multiple sentences in a tweet, we regard the overall tweet as coherent.