The appearance of a male's scrotum when he squeezes his testicles so that the skin is taught.
"Hey, lets get a picture of your squirrel brains on Blake's passed-out face"
by Rubbaneck November 16, 2004
when you push all your foreskin in a in a bunch and it looks like a squirrel brain, looks very nasty.
during a drunken night, I whipped my squirrel brain out and showed my friends
by revilo nworb July 14, 2013