There's a huge gray area that I was a part of once.

 A little over a decade ago, when I was in mid-20es, I knew a girl. We kinda were social, but not close; at some point, I asked her out, and we went for coffee and movies a couple of times. On probably our third meeting, I figured that we were social enough, and, basically, grabbed her breast when we were hugging; she thought we were not social enough, and asked not to call her since (which I did).

 If I were older and wiser, I wouldn't have done it; but, in my defense, my prior girlfriend didn't mind this advance, as we pretty much clicked at the first date, and I misread the situation the next time.
 
 The biggest problem with a lot of these thing is that the "unwanted" part is determined more by the person and less by the setting, and that sometimes doing nothing only wastes your time in a friend zone.