When you hit a guy/girl(charachter) in game,if he has a bad ping/sync(Bad internet connection/too far frocm server loc) usually does like this..
Example : If you punch Nukerstar(the guy in vcmp who has the fastest sync) or hit him with a car,he would get the full affect of punch/hit of a car..And he will be stuned down,therefore,he can be killed easily...