When you hear psssssssshhhhhhhhhhhh at a music festival you know you're close.. They sometimes try to mask it by lighting off fireworks and crankin em out. It usually doesn't last long at an open venue like in a parking lot. I've seen it time and time again. People will walk right up the sidewalk inhaling that shit like idiots. All of a sudden you'll hear, "five o, five o, five o!" and they scatter like roaches leaving nothing but sad, deflated, balloons all surrounding one spot lol. I guess you can't really get in that much trouble for it so its worth the risk to them. It's crazy how much money they make per tank. I've seen em go through a tank in 20 minutes with thousands of dollars in hand.