The internet has revolutionized work in ways we couldn’t have dreamed of just a few years ago, yet all that connectedness brings a lot of opportunities to goof off.

Why fill out that boring spreadsheet when the guy in the next cubicle is laughing his head off over the latest meme? Pretty soon, you’re clicking through your cousin’s vacation pictures … and half the morning has gone by.

Social Media Siren Song

Estimates show that nearly a fourth of the average American’s work day is spent on non-work-related social media activities, Inc. magazine reported last year.

The magazine suggests employers block certain websites and institute a cell phone policy to make sure workers are doing their jobs.

It might sound extreme, but without distractions, your employees will be forced to focus on their work more. — Inc. magazine

Extreme? That sounds like a no-brainer.

The Notorious Five

Here’s some websites that your employees almost never have a good reason to be on.

1. YouTube

You may like a good cat video as much as the next person. But that doesn’t mean you should be watching them at work.

2. Facebook

We know you have a tab open.

3. Twitter

Unless you are your company’s social media manager, you can wait until you are outside the office to see what witticisms people are posting.

4. Buzzfeed

A swirling black hole of animated GIFs, lists and links that will suck you in and never let go. Interesting? Yes. Any relevance to your actual work? No.

5. Tumblr

Huge chunks of this site are devoted to procrastination. Everyone posting on them is supposed to be doing something else.

Honorable mention: Do Nothing for Two Minutes. At least it doesn’t pretend to be something it’s not. And it’s relaxing!