For Yubiwaza, compare Monty Python's Mystic Welsh Art of Self-Defence, Llap-Goch:http://www.llapgoch.org.uk/
Paralyze an attacker with only one finger without any bodily contact! Clearly, flipping the bird has never been so powerful.
the first time I saw that Llap-Goch advertisement I laughed so hard I just about burst. So funny!