Share 'Horn with mind of its own'

My horn hasn't worked in the year and a half I've had the car. Last week I checked into it and found the fuse was missing. Easy fix I thought. Installed a fuse and both buttons on the steering wheel worked perfectly. The I backed out of the garage and as I turned the wheel the horn went off randomly. I assume the horn butyon are grounds that complete the circuit to make the horn sound. Why would…