shrimp brain 

Simply some one who is rather dimwitted and stupid or does something, says something idiotic or stupid.

Bob - Where did I put those keys?

Andy - In yer pocket, shrimp brain.

shrimp brain by Freedom Mine November 15, 2013

Shrimp brain 

Shrimps shit with their asshole, which lies on their forehead. So basically an alternative to "shit head".

-Dude, where's your apartment?
-You asked me for the 6th time this week you shrimp brain.

Shrimp brain by Phqu September 21, 2016