"Hopper" typically refers to a container or device used for storing or transporting something, often in a granular or loose form.
Here are some examples:
* Grain hopper: A container for holding grain.
* Coal hopper: A container for holding coal.
* Hopper car: A railroad car designed to carry loose materials.
While "hopper" might be used in a more informal way to refer to a container that collects something, it's not a common slang term for a toilet.