premise: A couple sitting at a reception table, the man is laughing as he motions back and the woman is laughing motioning forward. hypothesis: A man and a woman at a reception table are waving their hands at each other.
entailment: A couple generally refers to two people who are emotionally connect and may or may not be of the opposite sex. A man and woman may or may not be connected.  Laughing and waving are two different activities.