Extremely stupid person, someone who acts as if they've already donated their brain to science--before they die. Clueless. Dumb as a rock.
OK, what brain donor thought it would be a good idea to leave beer in the freezer overnight??
door JJRtwu2009 8 december 2008
1 more definition
a person who gives a lot of brain/head/blowjobs
Mary is a brain donor.
door stiff 10 oktober 2004