Narcan, or Naloxone, is an opiate receptor blocker used primarily in the pre-hospital setting by paramedics, but also ofton used in the hospital setting, to basicly erase any high you had from a dose(or multiple doses) of an opiate such as morphine or heroin. Its mostly used in a life threatening situation.
So, when you get that really bright idea to take some illegal drugs that could eventually make you stop breathing or choke on your own vomit and we(the paramedics) have to come save your sorry butt remember....all the dope you just took and that "wonderful" feeling you have is wiped smooth out in 10-45 second. Sucks to lose several hundreds of dollars in under a minute doesnt it? Also, dont get pissed and start swinging at us...the cops are on our side! Oh yeah, and some of us will swing back so dont chance it!
"I gave him two rounds of narcan, he came out of his drug induced coma and starting swinging. I grabbed the portable oxygen tank off the end of the cot and knocked his ass out! Kept him from dieing though..."