A man walks up to a woman in his office each day, stands very close to her, draws in a large breath of air and tells her that her hair smells nice.
After a week of this, she can't stand it any longer, and goes to HR. Without identifying the guy, she tells them what the co-worker does, and that she wants to file a sexual harassment suit against him.
The HR supervisor is puzzled by this approach, and asks, "What's sexually threatening about a co-worker telling you your hair smells nice"?