The superlative form of '
shitty', which in return is the adjective of the noun 'shit'.
Used to describe a place,
person, object or situation that is so incredibly
shitty, inferior, unpleasant, unfavorable, unfortunate, vulgar, despicable, anger-inducing, and/or mentally exhausting beyond any recognition.
The YouTube comments is the shittiest place you could ever be.
I
just had the most shittiest day ever.
I can't believe
the word 'shittiest' has
almost no definitions in the UD.