You work at Radio Shack, you should know a thing or two about electronics and computers. You should be helpful and courteous. Your job is to make a sale, your job is not to be a condescending dickhead who doesn't know what the fuck he's talking about. So when I stop in and casually ask if by some chance you carry any USB to HDMI products your response should have been along the lines of "I'm not familiar with any such product." What you should not have said was "Psh, no such thing exists. USB is only for input, you can't output anything through a USB connection. That's just for mice and keyboards and such."
You see, douchenozzle, USB does many wondrous things. Why as a matter of fact there are many forms of media that can be output via USB. That MP3 player there behind the counter, the computer OUTPUTS data to it via USB. Those external hard drives over there, the computer OUTPUTS data to it via USB. See that headset there? The one with the mic, hanging right there on the wall. The computer sends electricity THROUGH the USB port and cable to the headphones and, golly be, you can hear audio coming OUT of it! So yes, there are devices out there that allow the computer to OUTPUT video via a USB cable to a little box that converts the video and audio via HDMI connection.
In summation, before you act like an arrogant prick and tell me that there is no such device and that USB is not for output, why don't you go look through a fucking catalog, or work some Google-fu and learn a thing or two. Oh, and your boss, the lady who runs the store, yeah, the one who addressed me by name as she was leaving the store for the night, I'll be having a chat with her about your asshole demeanor.
Get fisted, cock-smooch!