Spot the Frippet: pig.

 Well, yes, there are these:

and these:

photo of a wild boar by Richard Bartz

but a dirty person is also a pig; and so is a mass of some metal such as iron or copper cast into a simple shape for ease of transportation:

By Mfields1 at en.wikipedia, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=14683032

In Britain, a task that's difficult or irksome is a pig (I hope that today won't bring you one of those), as is a salt container like this: 

Auckland Museum

Pigs are also often found in dining rooms. 

And not exclusively on the plates.

Spot the Frippet: pig. This word appeared as pigge in the 1200s. No one know where it came from before that, but the theory is that it's to do with the Old English picbrēd, which means acorn, which were used as food for pigs.

Pig iron is so called because when being cast the metal was often given the form of a long cylinder with smaller cylinders arranged at right angles down the sides, so they looked rather like a pig feeding its piglets.