Toyota Repair: Horn Malfunction 1999 Camry, loud horn, magic wand

Question
The horn on my 1999 Camry has recently been going off when it shouldn't.  It does this when I press the lock/unlock button on the keyless remote, but also randomly while driving down the road (Fun!).  I get a steady loud horn sound and it will only stop if I hit the horn pad and/or turn the steering wheel.
Thankyou very much for your help.
1999 Camry 4cyl 80K miles

Answer
Jim,
First of all THANK YOU very much for including the engine, year, make, and miles on your vehicle !!! 95% of the people don't.
I guess they think I can wave a magic wand with out knowing any of that information.

A spring or plastic piece is broken worn or loose behind the
pad. One must disable the air bag system before removing it.
I suggest you have a professional do that, its safer. You
don't want that airbag blowing up in your face.

Tim