Is it safe to discharge my body's static electricity onto my MacBook Pro?
That shouldn't be a problem at all if your MacBook is connected to the power source since it's grounded and by the way I wouldn't consider harmful to touch the MacBook body after being electrically charged even if the MacBook isn't connected to the power source. You have to pay attention only if you're touching directly motherboard components.

EDIT

My answer is not completely correct.
Check the comments