I recall a story about a wee boy, living in the wilds of Arkansas. Now this wee boy had two favorite possessions: his plastic black magicians hat and his track-suit jacket.
For some reason, one day he left his jacket stuffed into the magic hat on the covered back patio of his woodland home.
At some point later he returned to his prized possessions.
But what's this? Something is terribly amiss!
There was something brown on his jacket stuffed in the magicians hat.
Leaves, perhaps? A slug party? Who knows!
He investigated further.
And a rancorous smell, as if belched from Satan's own arse, burned his nostrils.
Poop!
He recovered his strength, clothing pin attached firmly to nostrils, eyes shielded by goggles. etc.
Poop, with maggots!
On his track jacket!
In his magic hat!
In the grand scheme of things, it may not have been the worst smell in the world. Durian, tooth decay, limozine seats, all carry with them foul, mature odors.
But it was the worst smell that that 9 year old boy had ever smelled, or will ever smell again, in the future, which is now, because I am that boy, grown man-sized.