Butter : adj. (word coming from butter). Drunk, drunk.
Buttered like a little Lu or a p'tit Lu (name of a little butter from this brand): dead drunk.
To be completely buttered: completely drunk.
The expression “Beurré” (like a little read): (Completely) drunk.
The adjective butter for "drunk" is a slang word which is a simple deformation of stuffed linked to the image of butter, the drunk person being limp or speaking "fat".
But why do we say stuffed for someone who is drunk?
The metaphor seems clear enough, since it suffices to imagine a container filled to its maximum, "stuffed" by its contents, as can be the man who has absorbed quantities of drinks.
If this expression dates from the beginning of the XXth century, one can all the same note that, in the slang of the printers, and from the beginning of the XIXth century, a "buttered" page was an overloaded page, soaked in black ink, everything. like one that is buttered, soaked in alcohol.
It remains to explain the little read :
Some people are familiar with the cookies called "small butter" made since the middle of the XNUMXth century by the company Lefèvre-Utile ("LU" for short).
These cookies are made with, among other things, butter, as their name suggests; they could therefore be seen as "stuffed" with butter. Hence the comparison in the form of a joke with the term butter from drunk.