There were nine of us talking about our experiences doing mock interviews with Miami University students. J.M. related a story of training an international interviewee about the history of the handshake - a gesture of peace (since you can't be holding a weapon while shaking hands). The cultural differences in handshakes (between opposite sex, who initiates, when done, etc.) are numerous. Other touch points are meaningful also - grasping with two hands, the shoulder tap with the other hand etc. Variations in firmness, grasp points and number of shakes can define personality and/or custom. It can be a introductory process, a congratulatory process, or even a close - as in a business deal.
In technology the term handshake denotes a connection between devices - a virtual way to say they are connected. In the case of the old modem - after the connection is established a squealing noise is emitted by both modems.
Next time you shake someone's hand - be a geek and squeal. :)