why are my head lights flashing and horn beeping?

What is your question?

While driving at night I clicked on the high beams which resulted in the headlights flashing and the horn beeping like a security feature. I pulled over and turned truck off but it continued to beep and flash. eventually the beeping stopped but the headlights continued to flash. I unhooked the ground on battery which seemed to fix problem for time being. This truck isn't equipped with any security other than power locks. What is happening? No service lights on dash either