I have without smelling it in any way, break an ampoule at Nova Rock Festival in an empty bottle can (Tip: a small stone with give in the bottle, because the ampule otherwise very hard breaks). Then we have a beer on offer in return for sniff at - and promptly to victims found. The responses were varied, ranging "smells in my toilet just" to "OMG, what have you done in there ?!". I myself then smelled it and was now not so overly shocked them. Certainly I would not recommend to break the ampoule in a closed and warm room and when one does not expect it stinks probably more. But, as some describe it later still as hell stinks up to 3 weeks, is really exaggerated. As you certainly no less smell a strong undistributed beer. I can not deny, however, that in between is quite suitable for a little fun (one of the "olfactory victim" has opened bottle thrown into a tent and thus the inhabitants relatively quickly chased out), but I would have liked the smell of the reviews here presented significantly worse. In addition, the price is relatively high, considering that the fun lasts quite short and the vials are hard to break, which at 9 piece about 1-2 unsuccessful attempts contains within itself.
Conclusion: a thoroughly witty and entertaining fun to make fun of, for example, not-unsuspecting and / or drunken festival-goers, but MMN relatively expensive, heavy and fragile not so idolatrous beastly stinking how much hand described. Those looking for a cheaper and more evil method to make stink, simply should be an egg a few days lying in the sun and then aufschmeißen: much cheaper, easier and with much more zerbechlich stench.