Jiu-jitsu can be handy in many situations including cases wherein solitary females are being harassed by aggressive men. Imagine being at a bar having a drink then a man suddenly tries to get too close. Instead of panicking, those who know a bit of martial arts can stay composed and use their skills.
Grip each side of the collar with forearms against the neck. Roll palms inward and pull them together to constrict blood flow in the carotid arteries. This does not require much strength but can effectively render the person unconscious, enabling a quick escape from the scene towards safety.