bird brain

Some days, for various reasons, I need to exit work through a set of double glass doors. They lock these doors at five p.m. and one has to go through a smaller side door, a fact which I am incapable of remembering. Today I crashed directly into the glass doors a mere fraction of a second after someone said, "The doors are locked!" because she knew, as everyone does now, that I would run into the glass doors. "Don't mind me!" I said, retreating through the smaller side door, "I'm like a bird slamming my head against a window! I never learn!"