Yes, Al, there is a lot of misinformation floating around. First, getting zapped by the HDPE sheet is an Electrostatic Discharge event. In our case, it is a small one. Another example of this is lightning. They differ in magnitude and in the damage they can cause, but otherwise similar. For a basic discussion on ESD, see
http://www.midwestesd.org/aboutesd.html
This link (
http://www.static-sol.com/61340-5-1/.../WhatisESD.htm) says "If two objects that have different voltages approach each other closely enough, charge may pass from one object to the other in a fast electrostatic discharge. While this only lasts a microsecond or less, the peak discharge current can be several Amps and the peak power can be in the kiloWatt range!" The high voltage means that even a relatively small current can generate enough power to cause damage. From what I can tell, Electro Static Discharge (ESD) waveforms are normally shown as a graph of CURRENT vs. time. As far as I can see, voltage in and of itself does nothing except initiate the event. Electrons must flow to do any harm. I suspected that it had something to do with the P-N junction and the electron depletion region - this link may shed a little light:
http://cnx.rice.edu/content/m1031/latest/
In terms of protecting the 'bot, I would think a 1 MegaOhm resistor in series with a conductive string or wire (we have some conductive string from some packaging or conveyor system) might limit the inrush enough. Put one on each corner of the 'bot, and grab this first before you handle it when it comes off the ramp.
If you want a very fast device to fashion a surge suppressor, I would suggest using a zener diode or Transorb (a specially adapted zener), possibly backed up with a varistor (slower but higher current handling) if there is real energy (bust open a PC surge suppressor outlet strip and use 'em) . A resistor/capacitor arrangement might also do the trick. I've seen all of these used in the 20+ years that I've worked in the electronics industry.
As to the effect of electricity on humans, the table in this link may or may not be accurate, but gives you an indication of some of the effects of various current levels on humans:
http://www.prl.res.in/~bobra/EARTH/html1/chapt3.htm
FYI, I've been zapped by 120 VAC a number of times and also by engine ignition coils in the 20,000 + volt range (not to mention electric cattle fences) . None was pleasant. I seem to recall that the body resistance was was approximately 7K Ohms, but that of course would depend on what parts touched, wet/dry hands, etc. At any rate, don't try this at home!