While law enforcement has other things to do than patrol for horns honking, and you more than likely won't be tossed in jail for the offense, you could still be ticketed and or have to pay a fine.
In Minnesota, we know there are all kinds of things we're not supposed to do when we're driving -- but do anyway (sometimes). From driving with snow on our car to checking our phones when we're stopped at a light -- to speeding and not turning on our lights when its raining...