What is the definition of Unknown Fumes?

"Unknown fumes" is a rather cheeky term for those mysterious, unidentifiable odors that can make your nose do a double-take and your heart flutter. Picture this: "The foghorn's unknown fumes wafted through the alley, sending passersby into fits of giggles and bewildered whispers." But let's keep this conversation light-hearted – even the unsettling can be funny if you're looking for a laugh. Here's a darker, edgier example: "The abandoned warehouse emitted unknown fumes that sent the firefighters into a panic, mistaking the stench of decay for a new kind of battle cry."