Cut out a tiny protest sign that says, “I refuse to work today! -Your Mouse,” and tape it over the sensor. Make this office prank funnier by adding tiny stick-figure co-workers picketing next to it.

As April Fools’ Day arrives, workplaces and classrooms are embracing lighthearted mischief. But the rule remains the same: keep it simple, safe and easy to laugh off. Here are some harmless prank ...