Red/Blue mini light bar for dash or windshield...?

Hi, I want to buy a mini light bar off Galls just for show and put it in my truck that looks nothing like a cop car or ambulance or anything else... it's a '84 dodge prospector. I don't want to use it on the road, just if I want to show some friends and for looks. Is it illegal in the state of MN to have it on my windshield, NOT turned on? Only answer if you actually know... and what are the consequences if I'm pulled over and the cop see's it sitting there not on? Will he just warn me to take it off or can I actually be arrested for just having it there? Here is what it is... a href="http://galls.com/style.html?ort=general_catalog&style=DL207" rel="nofollow"http://galls.com/style.html?ort=gener…/a