As Stephen wisely stated, until you figure out what is going on you need to disconnect the equipment for safety.
But a quick question, when you were receiving these shocks were you in contact with any other conductive surface? If you are wearing rubber soled shoes and not touching any other item except the camera, then the odds are extremely high that it was a static shock BUT that shouldn't be occurring if the humidity is high. If the shock occurs when you are touching the camera and some other portion of your anatomy is touching a conductive object then it is most likely from electrical leakage and that is a dangerous situation.
Under worst case conditions (i.e. contacting the live object with a piece of jewelry like a watch) while another part of your body is well grounded, then as little as 24 volts can cause heart fibrillation and death because the combination of the large skin contact area like jewelry combined with perspiration underneath it reduces you skin resistance to the point that even fairly low voltage can result in sufficient current flow to cause a fatality. With perfectly dry skin (DO NOT try this), getting across 240 VAC will generally not result in a fatal event, current flow is what kills and either increased voltage and/or reduced skin resistance results in increased current flow so these are the factors determining the severity of the shock and why what might appear to be a nuisance shock can easily turn into a fatal event. And counterintuitively, within a range a lower voltage can be more dangerous than a higher voltage because the lower current flow from a low voltage shock can easily put the heart into fibrillation and arrhythmia while the higher current flow that comes from a higher voltage source will stop the heart muscle which will often restart normally when the voltage is removed much like what happens with the paddles used by medical personnel. In short, don't be cavalier about minor shocks because they can be deadly.
I work regularly with equipment that has power supplies delivering up to several thousand volts with very high current capability so I am very safety conscious because with this sort of stuff you may not have the opportunity to make a second mistake.
Canon is a major manufacturer which has good quality controls over their own and their supplier's production but there are a lot of counterfeit items out there including those who steal the Canon name and logo. So even if your AC adapter says Canon, unless it came from a reliable dealer then it may not be something that meets Canon's safety standards. The same counterfeiters are not hesitant to put fake UL listing and European safety listings on their products either.
In one of your posts, you stated that the shock is occurring even with only the camera plugged into the computer USB port without the camera AC adapter/DC coupler connected. It is rare, but not as rare as it should be, for outlet grounds not to be properly connected to ground and if this is the case with the outlet where your computer is plugged in then its ground bus (including its case) and anything plugged into it that carries a ground reference (includes the shield of USB cables) can rise to a voltage above ground. While you are doing safety checks, ensure that your grounded outlet truly is grounded.
I prefer using a test meter but if you don't have one and aren't familiar with testing, most of the home improvement stores sell a little plug in device that will render an opinion on the health of your outlet and wiring. The reason I like using a meter is it would also be good to test that your PC ground (i.e. any metal back plate on it or connectors with a shield) are actually connected to ground via the outlet. An incorrectly manufactured or subsequently damaged power cord can easily have a break in the ground lead at either the outlet or equipment end. If you are not fully confident in your ability to test this yourself, then an electrician can easily check the outlet and also the PC for stray voltage on the ground bus. It isn't unusual for a ground bus to rise a few volts above true ground but it should never approach the level where it would ever be noticeable to anything except test equipment being used to measure the level.
There is a very good likelihood that what you are seeing with your Canon camera is a symptom and not a cause of the problem.
Rodger
EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video
