How to wear a short-sleeve button-down without looking dorky
Pocket protectors, weird half-tucks, and tent-like fits are probably what come to mind. But it doesn't need to be that way.
You can look as if you weren't picked last for dodgeball; you just need to follow a few guidelines.
Most important, the shirt needs to fit well. Fit is the most important aspect of any garment you wear, but it is even more crucial for short-sleeve button-down shirts, which have the capacity to look like a sad sack when not correctly fitted.
The body should be close-fitting but not tight, the sleeves should end before mid-bicep (this is very important), and there should be a minimal amount of flair in the sleeve. It also shouldn't be too long.
The collar is also important. Button-down collars are easiest to wear, as the convertible collar, which lacks the supportive back, is less structured and a little floppy.
Second, the shirt needs to be the right color or pattern. Short-sleeve button-downs allow a bit more freedom, so don't be afraid to get creative.
Subdued Hawaiian-style shirts have been particularly hot lately.
Third, keep in mind that short-sleeve button-downs cannot be worn every place that long-sleeve button-downs can. They are a replacement for a T-shirt, not for a long sleeve. They sit somewhere between them in formality. Don't be surprised if your boss looks at you strangely when you walk in wearing one.
Ryan Gosling in the above photo perfectly nails all three of these guidelines, and he looks great because of it.