The mining industry opens all sort of doors for this kind of thing... I've personally seen: Liqui-pol in shampoo bottles, makes water go slimy and takes FOREVER to rinse out stench gas in a house (we stunk out an entire town with this stuff once....) those luminous chemical tubes cut open and splattered above someones bed. A can of shaving cream frozen, opened then put in someone's window Squid stuffed in A/C vents, Prawns shoved up the handset of a two way mic coffee put in the sweat-band of the hard hat, they sweat, big brown stains run down their face... live and dead mice put in jacket pockets, desk draws, gum-boots ect.. live and dead snakes put in jacket pockets, desk draws, gum-boots ect.. electric fence unit hooked up to core-trays, cars, urinals, ..ect Toenails in rollie tobacco various sharpened objects paced on or inserted into chair foam Horse hair threaded into a ciggie, match-heads put into ciggies Someones hard-hat urinated in every night for 4 months A w@nker's akubra put into a drill-sump (bye bye Mr hat) only to have the sump pumped out 6 months later...(hello Mr hat) Grass seeds in shag-pile carpet, and a light water...Alfala seed would have been better, faster growing. A saline drip-bag set up so when someone sits on the drivers seat, it squirts him in the ear. windscreen washer jet relocated to inside cab, aimed a drivers face Small wire from Ign coil run to lower seat squab. (didn't see if this worked, left site next day) A+B foam (expanding foam) bombs made and placed in cars, houses ect um...and lots more I've forgotten....