Another one relating to guns: When loading a revolver, why is it always necessary to spin the cylinder? And why does the cylinder always make a "zzzzzz" sound when it's spun? I've never heard a cylinder make a sound on a real revolver when it's spun.

Here's one I hate with computers: The "boop boop BEEP" sound effects that they always have when someone is typing on a computer keyboard. Movies could probably get away with this in the very early eighties before most people used computers, but today it's just stupid. Closely related to this is the "zoom in" sound effect that always accompanies image processing software sequences. I use image manipulation software all the time, and when I zoom in on something or crop an area, Photoshop stays dead silent. Maybe I need to upgrade to Photoshop CSI or something. Closely related to this is the ability to enhance low quality security camera footage to the point where someone can zoom in on a reflection on a doorknob on the opposite side of a large room to see the face of someone standing out of view of the camera. Sorry, but pixels just ain't that flexible in real life.

Another cliche that bothers me to no end is when people are running from a badguy/monster/evil government agency/whatever, and they run into a building and run UPSTAIRS. Just where the heck do they think they're going to go? Once they run out of more "up," that's it. It's just dumb.

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Yes, they laughed at Einstein, but only because of his silly hairstyle; no one was actually laughing at his science.