Stand on a mirror. Your reflection will be flipped vertically along the y-axis. Your reflection will be upside down relative to you. The flip happens perpendic

Stand on a mirror. Your reflection will be flipped vertically along the y-axis. Your reflection will be upside down relative to you. The flip happens perpendicular to the surface of the mirror. That's what trips everyone up. They think that a flip happens parallel to the mirror, but the flip happens into the mirror. Like flipping a glove inside out.