system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does sneaking up and knocking someone unconscious from behind really work? Is it at all like in the movies?
gpt
No.  A blow to the back of the head/neck can knock someone unconscious(like in the movies) but it is highly likely to lead to some damage or even death(oddly they never show that).  It used to be not uncommon for police to carry blackjacks or the like to deal with unruly suspects in this manner but it was fatal far too often and the practice was phased out.