Usually retarded people that thing their smart but their not. They usually have small brains and just say they have big brains to make themselves feel better.
by gamergurlbathwater420 November 18, 2019
Get the big brainsmug. Look! Jeff just pulled a big brain by jumping out of a three-story window to beat his sister down the stairs.
by Big Brain Joe May 21, 2021
Get the Big Brainmug.