A banana surprise happens when a male is mid coitus with his female partner in the dark and says " Do you mind if I try something different?" After getting permission said male then reaches for a banana he has stowed earlier, peels it and then begins gently rubbing the banana on the females genitals. After a few minutes said female should ask what is that which then the male yells "Banana Surprise!" and shoves said banana into the females vagina at full force.
My girl said she was into magic so I Banana Surprised her ass.