It's shown as being in the kitchen, closet, and bathroom, both prominently and easy fast access.
It has to be some kind of cleaner product.
Yes i'm giving it the benefit of the doubt for it not being a sex toy, though it could be since we never see it used.
It plumbs obviously, that's how it gets the name plumbus.
Item 1 in image attached is the piece you insert into the drain, it's soft to allow easy insertion, but it expands to fit the drain which helps to remove all debris.
Item 2 is the handle which you use to move item 1 up and down once inside the drain.
Item 3 is a brush for cleaning counters, sinks, bathtubs, or any other surface you'd like to brush.
Item 4 contains the complex inner workings of the plumbus, but also allows for easier storing of the plumbus, as you can see by the way it's held on the patented plumbus holder™
I feel like it'd be used to flobulate stuff that doesn't on its own. Elsewise, why outfit it with a gerble? Plus, look at that swollen worbo: they don't get that big unless you really have to shniggle something.
It seems awful obvious once you pondulate it, OP.
>doesn't know how to use a plumbus
I fucking hate this generation.
It can't be that bad since Morty has one... or he used to anyway.