the fusion of these two popular uses of "
brain":
1)
blowjob;
head;
dome;
oral sex
2) the brain-like appearance of a
scrotum when pulled through a pant zipper to show to unsuspecting bystanders
coupled with a unique pronunciation of "brain" which incorporates dramatically oscillating vocals has yielded the following definition:
n. oral sex performed on the scrotum; gargling a nutsack; sucking on some balls
"holy shit dude! leslie gave me some steamy brayayain on her front lawn after homecoming!"