Shitest or Shitty = the worst around
Commonly confused with the meaning of "The Shit". The important part of this is without "THE" an entirely different meaning applies.
For example:
1. That concert was shit! = Horrible concert
2. Dude, that concert was the shit! = Great concert
If you apply THE before shitest/shitty you are NOT changing the meaning like shown above. You are simply emphasizing how shitty (horrible) whatever you are referring to.
Example:
1. Wow, your boyfriend forgot about your anniversary? That's shitty. = that's fucked up, break up with him.
2. Bro, you live on the shitest side of town. = Your parents should've picked a better place to raise you.