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??
by JJRtwu2009 December 08, 2008
a person who gives a lot of brain/head/blowjobs
Mary is a brain donor.
by stiff October 10, 2004