In December of '02 I had a similar problem. My lady friend had borrowed my
96 SC2, while her car was being serviced. Sometime after parking the Saturn in her driveway, she kept hearing a car horn. She became annoyed and went outside to find that my car was the problem. She tried the steering wheel buttons to no avail. Then drove the honking car to a gas station. There a kind service person pulled the fuse for her, at no charge.Later I put the fuse back in and had no other problem. I did however replace the horn myself. I figured that it was only a matter of time until the problem occurred again. The part cost $47.
Before I replaced anything, I talked to the parts man at my local dealership. Being an older guy, I thought it could be the horn solenoid. On older cars, if a horn button was not stuck then probably the culprit was a stuck solenoid. A solenoid is simply an electrically operated switch, which receives a low current connection from the horn button and provides a high current connection to the horn. I found that my Saturn has as integrated horn/solenoid assembly. In other words, replace the horn and you are replacing the solenoid.
On my car, the assembly is located within the drivers side front fender, below the headlight assembly. It is accessible from below and is relatively easy to install after you remove and/or loosen two or three of the plastic under-car and wheel-well shields.
Jim