When a person sees an event or an image that is so horrible they will never be able to forget it.
I walked in on my parents having sex and got instant brain burn!
by Rmc0315 December 25, 2011
The sensation of severe burning in your sinus when something nasty makes its way up there, for example, horseradish, and even worse, wasabi.
Oh wow, this bowl of noodles looks good, lets put some wasabi in it...*slurp slurp*...OH GOD MY SINUSES!!!BRAIN BURN!!!
by General Specific September 22, 2008