1.) to ejaculate profusely. "Brains" referring to slang for testicles.
2.) Refers to the slaughterhouse process of removing the animal's brains with compressed air forced into the skull through the hole where the spinal cord enters. The brains are then packed and sent to markets in Korea and China as food. This term appeared in the February 4, 2008, Washington Post article titles, "Inhaling Pig Brains May Be Cause of New Illness."
"Last week I went for a massage and the girl had me blowing brains all over the place!"