If there is a short circuit within the computer, you should not feel anything since the computer chassis should be grounded through the power supply cord to earth ground. If this is the case, then you should stop using the computer immediately and have an electrician check the wiring in your house.
If you have unplugged the system and let it sit for a short time or pressed the power button several times to ensure the PSU caps have bled off, then there is no way you should feel any sensation. If you are, it's your imagination or something to do with your body's nervous system.