At a university somewhere near you
At a university situated in Wales somewhere between Gymru and Cymru there was (and still is) a very traditional biology department. It has all the things one would normally associate with uni biology departments: lab assistants that make Pratchett's Igors look sane, equally deranged staff and a curiously lackadaisical take on health and safety.
This attitude came back to bite them one day, when it was decided that as a particular project was over, the bulk of the particularly vile and smelly thiol compound they'd been using really ought to be gotten rid of rather than merely leave it to fester on a shelf somewhere (this gem of wisdom being dictated by someone finding the best part of a three-pound jar of picric acid on a shelf in a store room; dry picric acid at that meaning a good kilo of sensitive high explosive needed getting rid of).
So, it was decided to find the nearest sluice to the main sewer and flush it down there, rather than pay for proper disposal. Unfortunately this particular thiol was rather oily, hydrophobic and had a high vapour pressure, and smelled very like rotting fish multiplied several thousand times. It flushed away easily enough, and was followed by a bucket or two of hot Decon-90 detergent, and that was that, or so they thought (wrongly).
The stuff apparently stuck to the inside of the sewer and over the following months evaporated off and crept back up into the lab drains, which had no water lock system. Everybody knew which genius had decided to dispose of things that way, and he spent those months as the Least Popular Man Ever.