Plugged in Pigtail - Goofy Image

This one comes up often enough that I thought it warranted some time. Often when you plug in the little pigtail for your LCD projector and turn it on you'll get either a weird picture that is on your computer somewhere or else a computer-looking image, like the startup screen image. Apparently your Mac has a folder where it pulls those images from and the image it's showing is the first one in that file. To remedy this go up to the little TV screen in your Taskbar (top right) and Turn On Mirroring. This should take care of it.

If you can't see the little TV screen then go to your System Preferences (under the Apple menu on the top left) and inside System Preferences choose Displays. Under the Display tab make sure the box next to "Show displays in menu bar" is checked. You can also adjust the screen size here if you get a funky screen after turning on mirroring.