Why sometimes we could get shocked but not always?

[kenny1999]

I did a check on Google, it's said human body is an electric conductor so we should always handle electricity with care by common sense. I sometimes accidentally touch the metal of the USB charging port when I unplug my fully charged smartphone but I don't get electric shock. What is the reason behind? Is it theoretically there are some electrons that have gone through my body but they are not enough to cause a feeling of electric shock?

In other words, why sometimes human body could get electric shock? Even if we are electric conductors, but we don't normally stand on metal ground, how can we form a complete circuit for the current to flow through?

Edited December 12, 2022 by kenny1999