"no more of those little candy fish, thanks"

It is a propaganda poster aimed at workers, it the worker is saying no to a glass of alcohol, probably moonshine, and the text says the following:

NEJ

Valborg är ett borgerligt påhitt.

Kom inte bakfull till första maj.

Here is what I believed was the original poster:

I have now read more about it, and it seems that the poster is a repurposed Soviet anti-alcohol poster from 1954.

Here is the original Soviet poster:

I don't actually know the origin of the Swedish poster, if it actually was used in the past, or if it is a meme created from the original Soviet poster.

Anyway, the translation of the Swedish version above is:

NO

Walpurgis is a bourgeoisie creation.

Don't arrive drunk at mayday.