I've seen a guy wear a yamulka and a visor before. It makes perfect sense, especially if you want to observe your religious laws as well as keep the sun out of your eyes during the summer. The Yamulkap does the same mix and match, except it attaches the kippah to the visor, so you only need to keep a single piece of accessory around.
We're not sure how your more observant elders will react to the decidedly modern take on the traditional skullcap. Since it's designed to help you keep up with Jewish tradition while shielding your eyes and forehead from the damaging rays of the sun, they might give you a pass. If I were in their shoes, though, I'd kick your ass for wearing something that's made from 100% cotton yet looks 100% retarded. Just sayin'.
When I first saw the Yarmulkap, I was wondering what the hell that baseball cap was doing with three large holes all over it. Were they provisions for three-horned monsters who want to wear a cap? Was it something for people with head injuries? Well, alas, it was way cleverer than that - it was a sun visor attached to a yamulka by three sewn strips of fabric.
Just like the most genius accessory ever invented, the fanny pack, I'd reckon you'd get more laughs than admiration from wearing this. But I bet you don't care because you're cooler than that. Plus, it's only $12.95 apiece, so you can easily charge it to experience if it ends up ruining your date - like the guy in the photo is doing.