There are plenty of ways to go about subjecting your friends and family to antics, but every now and then you may run out of fun ideas. If you are searching for some ammunition for an April Fools prank today, then one option is to look no further than your intended victim’s Mac. 

If someone uses his or her Mac regularly, then you can tackle their system with a few changes that may give you a chuckle or two. Since OS X is a multi-user system, to effect any change you will have to quickly access the system when your intended victim is logged in, and sometimes to do that you might have only a few seconds to jump in. However, if you follow these steps you should be able to get your prank set up and ready in minimal time.

Full Screen screenshot

The first option you can do is to mask your victim’s display with a full screen screenshot. This can be amusing since the display will look as the person left it, but nothing on it can be interacted with:

1. Press Shift-Control-Command-3 to save a full screenshot to the clipboard.
2. Launch Preview by pressing Command-Space, typing “Preview” in Spotlight, and opening the program.
3. Press Command-N to create a new image from the clipboard contents.
4. Press Control-Command-F to make the new image fullscreen.

Rename applications

If the person uses one or two programs regularly (like a favorite game), then you can make it open another application instead:

1. Go to the applications folder and rename the favorite program.
2. Select another generic one (like TextEdit) and press Command-C followed by Command-V to make a copy of it.
3. Rename this one to be the name of the first application.
4. Get info on the favorite program and copy its icon from the top of the info window.
5. Paste this icon to the newly copied program’s info window (select its icon in this window before you can paste it).
6. Remove the favorite program from the dock, and replace it with the new copy.

Now when the person clicks their favorite app, the copied program will open instead.

Invoke Text to Speech on a famous speech

You can create an automator workflow that will run when a user logs in, which can be used to speak a phrase or two, or an entire speech if you want:

1. Open Automator and create a new Application workflow.
2. Drag the “Get Specified Text” and “Speak Text” actions to the workflow area.
3. Copy a famous speech (or any text you like) to the “Get Specified Text” action.
4. Save the service with some generic name.
5. Drag the application to the user’s Login Items.

Now log the user out of the system, so when he or she logs back in, the workflow will run and speak the speech.

Change the keyboard layout

Most people use a standard QWERTY keyboard layout; however, OS X supports a number of international keyboard layouts, or alternatives like the Dvorak layout. These will change the characters typed on the keyboard, so you can do this to quickly throw a little confusion in someone’s direction:

1. Go to the Keyboard system preferences.
2. Click the plus button in the Input Sources tab.
3. Add a new layout to the input source list.
4. Check the box to show input menu in the menu bar.
5. Access this menu and choose the new keyboard layout.

Any other Mac pranks you know of that were pulled on friends and colleagues (or perhaps yourself) this year? Post them below in the comments.