Approximately 90% of communication with others is expressed through nonverbal cues, including hand gestures, facial gestures, and insinuation. So if you have a major crush on a girl but don't want to tell her yet, but come in for a hug that squeezes the life out of her, she'd more likely than not realize where you're leaning towards.
How you hug a girl is extremely important because it shows her what you think of her as: a friend, a coworker, a crush, or a potential girlfriend.
You might not know this, but there IS a WRONG WAY to hug. Learn the right way in this video.