Handshakes can be messy, awkward things. First, there's the problem of whether or not to shake hands. Then, there's the problem of what to do if the person whose hand you try to shake isn't on your wavelength. Finally, there's the fleshing fumbling that comes with actually trying to lock hands in anything resembling a normal handshake. Hence the ubiquity of the high-five: why attempt to graciously dock your mitten in someone else's when you can simply slap them together instead?