Stop the Extension Change Warning in Finder

If you are changing file extensions often, perhaps to put a file in the left-hand side of the dock, then you'll understand why it's really annoying when you have to confirm that you really want to change the file extension. To turn off this safety "feature" you just need to uncheck a box in the finder Preferences. Go to Finder>Preferences (Cmd-,) and click on the Advanced tab. Then, uncheck the box next to, "Show warning before changing an extension".