Take a normal shotgun and walk directly up to a Rhino. Use manual aim and fire directly into the Rhino. It will spurt blood as if it were a person. This can also be done with other cars and objects, but is best when the Rhino is the target, because it will not explode. This works well at the airport so you do not get a wanted level. Note - The blood only spurts when you fire from certain angles; down and to the right slightly works the best, and you must be directly up against the tank and use manual aim to do it.