seagull brain Share definition Flag A person who does stupid things, but in a funny way that makes you love them even more. Rory was a Seagull Brain for believing Colin would actually pay him $5 for jumping the the MacDonald's dumpster naked. seagull brain by Amelia Rose December 7, 2006 0 0 Get merch Get the seagull brain mug. Buy Now — $32.95 See more merch