The outfit that the average American wears to work has undergone a radical transformation over the years.

When Mad Men first came on the air, one of the things everyone talked about was Don Draper’s style and how the show harkened back to a time when men wore proper hats every day to work (and smoked and drank in the office!). The suit and tie dominated most of the 20th century. In 1966, a trend called “Aloha Fridays,” in which workers were encouraged to wear colorful Hawaiian shirts at the end of the week, caught on a little bit. Then “Casual Fridays” exploded in the mid 1990s.

But even the outfits most guys wore on Casual Fridays were only casual in relation to suits. Khakis and a button down shirt, which became the signature look of Casual Friday (often in really atrocious fits), could still be considered dressed up in some circles.

The reins really loosened (and may have been let go of altogether) with the rise of startup culture. It started with the first web boom at the turn of the century and only grew as Silicon Valley became a true international business capital. Almost every early profile of Facebook founder Mark Zuckerberg made mention of his “uniform” of Adidas flip-flops and a hoodie. Ditto for Steve Jobs and his New Balances, mock turtlenecks, and dad jeans.

In some ways, the extreme relaxation of workplace clothing rules was Silicon Valley’s way of telling the business establishment, “Fuck you, I’m in the three commas club and I wear flip-flops everyday.” In some ways, it was practical. If you can code in your sweatpants on your couch, why change when you go into an office?

Now with summer in full swing, another formerly taboo piece of attire is making its way into offices. I’m speaking, of course, about shorts. In recent years, designers have sent short suits (regular length jacket with shorts) down the runway. And on those days where it feels like the heat punches you in the nuts when you walk out the door, the comfort of shorts can be particularly intriguing.

Don’t do it.

Seriously, just don’t. There is a difference between work and the rest of your life. The divide between those two may have blurred a little bit, but there is still a line between the two and shorts are on the “rest of your life” side of the line. Chubbies shorts established a successful business trying to capture the spirit of Friday at 5 p.m., not trying to bottle the feeling of Tuesday at 8:45 a.m.

No. No. No. No.

No. No. No. No.

For one thing, wearing shorts to work instantly makes you “Shorts Guy.” Your co-workers will notice. It probably won’t be a big deal to most, but you will definitely get comments like “What, no shorts today?” from whoever the Lumbergh in your office is. That gets annoying real quick. The best outfits attract attention, they don’t call out for it. Shorts have a habit of doing the latter.

It’s also a very hard look to pull off. Shorts are so casual that everything else in your outfit needs to be more formal in order to make it office appropriate. Shorts with a T-shirt and sneakers works great on the weekend, but at the office it screams IDGAF. While designers have created short suits, I’ve never looked at a guy wearing one and thought, “That’s a look I want to copy.” The balance of the jacket with the shorts results in an awkward silhouette, in my opinion, even in Bermuda (see photo above), home of the Bermuda short.

Then there’s the matter of your legs. We had a long winter. Now that the weather is finally getting nice, the last thing your co-workers want to see are your pale stems. If you’ve got a body like an Olympic swimmer and spend a lot of time grooming and toning your legs, you get a pass. For everyone else, keep your kneecaps to yourself. (It should go without saying, but the same goes for your toes. Unless you’re a pro surfer, no flip-flops at work either.)

And remember, the comfort that shorts provide on a hot day can disappear the moment you enter an office with the AC blasting. On top, you can wear your summer best friend, the short sleeve button down, and throw a sweater on if it’s cold. If you’ve got shorts on, what are you going to do? Put a crocheted Afghan on your lap like great aunt Bernice?

When you go to work the key is to be neither overdressed nor underdressed. That way you can slide into any situation confident that your appearance won’t raise any eyebrows. CEO calls you up to his office unexpectedly? That cute girl five cubes down asks you to grab lunch? You don���t want to be in a situation where your first thought is ���I’m dressed inappropriately.” If you wear shorts to work, you will always be in that situation.

Justin Tejada is a writer and editor based in New York City. Follow him on Twitter at @just_tejada.