Security measures
He's relieved that the security measures here don't extend to a fingerprint or iris scanner, and he remembers Isaac's proposal for a biometric identification system which required the user to perform thirty seconds of oral sex on an androgynous piezo-electric tubercle, on the basis that any given individual's precise oral sex technique is both unique and impossible to teach or imitate.
(Glow by Ned Beauman, p.119)