Definitions by emo4ever

mustard brain 

the word your mom uses when shes mad at another driver .

Mom: you mustard brain pee knuckle !!!!

mustard brain by emo4ever January 8, 2022

mustard brain 

the word your grandma uses when she is mad at someone.

grandma: YOU MUSTARD BRAIN PEE KNUCKLE!!

mustard brain by emo4ever January 8, 2022