April Fool's is a great time to let off steam with a good practical joke.
But if you're at work, you have to keep your pranks practical and safe for the office. And by that we mean they should cause no permanent damage to employers' or co-workers' property (or psyches), and should not involve any activity referred to in the Employee Handbook as "grounds for termination." Also, no mean-spirited personal attacks.
With that in mind, here's a list of 5 classic pranks that (usually) won't compromise your job security: