The most smelly or stinky.
This word makes people think of bad smells and something that is not nice.
Examples:
The garbage can is the stenchiest thing in the kitchen.
That flower is the stenchiest one in the garden.
The stenchiest socks are under the bed.
The stenchiest cheese made everyone leave the room.
After a week in the sun, the fish was the stenchiest thing ever.
The stenchiest skunk in the forest made everyone run away.