Can you wash uggs in a washing machine?

Hell yes. Hopefully your uggs will be destroyed in the process, thus saving the world from the sight of at least one pair of bogan shoes.

But seriously, they're wool (or should be, otherwise you won't have the authentic feeling of having your feet up a sheep's arse), and wet wool shrinks when it dries. So go ahead, throw those babies in the washer and go and buy some real shoes. Or go barefoot - frostbit is surely preferable.