Thats ridiculous. Can't she first try sneaking through a window in the back of the building, such as a toilet window, or at least attempt to find a back door before paying? Or just cause a disturbance somehow for a distraction?
Ammonium polysulfide should do the trick. Take some ammonia solution (weak over the counter crap will work for this), get some caustic soda, some ammonium sulfate from a garden center, the sodium hydroxide might need to come from a DIY store, the ammonia water should be findable there too. Rig up a bottle with a tube and cork that fits. Mix some dry caustic soda prills, caustic potash (potassium hydroxide, KOH) will do the trick too), the rubber tubing goes through a hole drilled in the cork, and then add a little water to the mixture of ammonium sulfate and caustic, which should be intimately mixed. This will cause the stronger base (the alkali metal hydroxide) to displace the weaker one (NH3) from the salt, leaving sodium or potassium sulfate and ammonia gas, this passes through the tube, and into the aqua ammonia, to concentrate it as much as possible.
And take agricultural sulfur, known as flowers of sulfur, or it can be found at pet shops and vetinary type outlets that cater to the public, in the form known as roll sulfur, basically round cast sticks of S, this should be ground, however agricultural sulfur is a powder usually, found sometimes also in sulfur candles intended for fumigating greenhouses, Fuze this with metal turnings, doesn't matter a great deal what. iron filings will work alright, using a blowtorch (releases lots of sulfur dioxide, unless you get a tank of welding argon, just cheap disposable ones, those aren't expensive, or CO2 or nitrogen, both cheaper), you could also melt sulfur onto lots of wire wool if you can't find filings, better would be to order some powdered iron on ebay, OR, best of all take caustic soda, and powdered sulfur and heat them together to give sodium hydrosulfide. Do this outside as when NaHS gets wet.
Then react the hydrosulfide with the strong ammonia solution, just mix and leave to sit and stew in a container, OUTSIDE.
This will create ammonium polysulfide, a yellowish, oily looking liquid. And it STINKS something heinous. Be aware that the rxn of the sodium hydrosulfide with ammonia solution will release hydrogen sulfide, do not breath it in or allow to come gusting up at the face, it is very toxic if inhaled. So when opening the container, after its been stewing until its needed, keep your face away, hold breath, do it outside and retire a bit, away from the open container to let any H2S blow away. The ammonium polysulfides can then be decanted and put in a sealed container. A little glass bottle would be ideal, and this poured on the floor near the entrance. Will distract people pretty damn well because of the putrid stench of rotting eggs and sewer-fumes it gives off, with acidic and acrid undertones. A pretty effective stinkbomb.
Or, you could do the exact same process but order some selenium on ebay. Don't use tellurium, because that would leave innocent bystanders contaminated for a long time and terribly, awfully. People have actually killed themselves after becoming contaminated and getting tellurium-breath, but to the best of my knowledge its specific to tellurium. Tiny quantities of Te absorbed will do that. But where sulfurous things smell bad, the equivalent selenium compound will smell absolutely gutwrenchingly, brutally, teeth-meltingly, toenail-knottingly hideously shit-your-britches noxious.
