Working as an assistant to a surgeon who has to cauterise human flesh with a red hot wire. The smell of burnt human flesh sticks to your nose for hours. Even when you are exposed to it often I could not always stop vomiting afterwards. And the scent burns itself into the brain and memory. it is horrible.

I live with cats, they can produce the foulest odours in their litter trays, just because you said no to them!

A dead skunk, decomposing and stuck under a portable classroom floor. 🤮 😷

I was in New York and ordered a burger from room service. Unfortunately, it arrived with a massive hunk of braised cucumber on the side. (What’s the one thing you can do to a cucumber to make smell/taste worse than it usually smells/tastes? COOK IT, THAT’S WHAT!) The stench was truly awful. I thought about flushing it down the toilet but it was too big, and I didn’t want to have to call maintenance because I’d blocked it. (“Honestly, mister plumber, it’s a cucumber stuck in the u-bend…”) So I threw it out the window. I didn’t hear yelling so I don’t think it hit anyone.

My dog's fart.

I was on a site for work that recently had a rat infestation... while I arrived after a lot of work (removing and cleaning things up) it still stunk something special.

I volunteered at a hospital, in the transport department (moving patients - wheelchairs and stretchers and whatnot) the transport office was in the basement - right next to the morgue, and depending on how recently the door had been opened you caught some stench

Opening a septic tank