Also, a painful blow delivered to the outside of the thigh (along the vastus lateralis muscle, if possible) with the raised middle knuckle of the assailant's dominant hand. The aim is not so much to bruise as to cause rapid and extreme contraction of the muscle, resulting in sudden falling over and cursing.
"Oy, arrgghh! He fookin noogied me! I'll be crippled for hours!"