2003 Oldsmobile Alero Bought 2 weeks ago

2003 Oldsmobile Alero 4 cyl 61,000 miles

I bought this car two weeks ago from WY and traveled to MO. When I was driving, the car horn just went off and conintued to until I hit the car horn (not hard I assure you) and then it stopped. The car horn went off again 12 hours later when the car had been unactive for several hours, was not on and had no key in it. It went off again four hours after that, all times of which I had to hit the car horn to get it to turn off. It must have went off again and I didn't hear it because in the morning it would not go off at all. I assume the car horn is burned out. We took out the fuse later to guarantee a peaceful night for my neighbors but was wondering what is wrong with it before I take it to a dealership.