Shorter term of shitting bricks when one is nervous.
Muscle Man Randy Savage is brickin it because he's about to get pulverized by The Rock.
by UNVME666 November 22, 2011
v. to be extremely erect and have so much blood flow in your genitals that you are hard as a brick
Justin was brickin' it in the scholastic bowl van around noon that Saturday.
by Raptor Jesus April 22, 2007