Hahahaha! NICE!
That happened for a while in my dad's truck, it would just start honking for no reason.... People would look and we'd just wave at them and smile. HAHAHA! /forums/images/graemlins/rotfl.gif
I'll bet it's shorting out in the steering column somewhere. If you take off the horn button or the cap on the steering wheel it's probally arc-ing and shorting to ground somewhere in there. Theres a spring that's supposed to hold the cap up so it wont honk until you push on it.
You can disconnect the horn relay or the wire to the horn to get it to stop honking for a short term fix, but you might have to take off the steering wheel with a puller to be able to track down where the wire is shorting out. /forums/images/graemlins/thumb.gif