Hacky Sack playing is usually not associated with dangerous activities, but that could change for some people. The Fire Footbag is made from flameproof Kevlar fibers, and you simply soak it in kerosene before you light it and start kicking it around.
Now, to me this sounds like a not so bright ideal, and someone is sure to get something or someone on fire. But then again I am not a skilled Hacky Sack player, so I cannot account for playing abilities in the safety equation. Still, I have seen even the good players mess up on occasion, without the flames as a distraction. The video is pretty cool to watch, but even the skilled players catch their foot on fire.
If you insist on unnecessary and dangerous risks playing a simple game you can find the Fire Footbag for around $25.