This is the same old trick which is done on Windows system and can be done on Mac system as well. You can prank your colleagues that your Mac desktop has frozen.
Step 1: Minimise all the application and take the screenshot of the desktop with all the standard icons.
Step 2: Take a screenshot of your desktop and save the picture.
Step 3: Right click on the desktop and select Change Desktop Background from the context menu.
Step 4: Set the desktop screenshot as background for your desktop.
Step 5: Navigate Finder window, select Preferences from the menu.
Step 6: Navigate to General tab and make sure to un mark the checkboxes under the section “Show these items on the desktop”
Now your system will display the desktop background but none of the items will be clickable.
Also See: Display hard disk on desktop