An affectionate nickname for Nestlé Nesquik, which is a chocolate sauce that comes in a bottle resembling a bunny. When one turns the bottle upside down and squeezes it to get the sauce out, it appears as though the brains are being squished out of the bunny, hence "bunny brains".
Could you pass me the bunny brains? I want some for my milk.
by Phalloidium August 18, 2008
n. insult. a person behaving especially belligerantly.
"You didn't mop the floor like i told you to. Stupid bunny brain."
by Lunarose October 21, 2003