bear hug (but not the good kind)

If your attacker tries to "bear hug" you—a common type of move when it's a male attacking a female, says Campbell, where the attacker grabs his victim from the front or behind around the shoulders—your first reaction might be to grab his elbows to try to pry arms away from your body. However, your best defense is to drop as low as you can toward the ground and squirm as much as you can to wriggle out of your attacker's hold, advises Campbell. 

"Think about how a cat would respond if you put it in a tub of water," she says. "You want to act like that cat—be as difficult as possible to control." Lowering your center of gravity has another big benefit: It makes you more stable and harder to lift, and it gives you a new angle from which you can knee-strike, groin-kick, or throw a punch or elbow to your attacker's eyes, throat, neck, or ears, giving you more time to get away.