When someone rips a nasty fart in another person's bowl piece of a smoking apparatus while they are torching whatever may be in it. The name is a reference to the nuclear disaster that happened in Russia in the 80s, Chernobyl.
noun - "Joe, why did you have to fart in my bowl and turn it into a Chernobowl? That's just gross."
verb - "JOE! You totally Chernobowled my hit. You're paying my next medical bill."