Phantom brake lights

What would make the brake lights come on in my 2006 vehicle while the truck is at rest in the garage?

A faulty brake light switch.

Thank you for your response. The switch was replaced at the dealer 2 weeks ago. The tow package wire harness was inspected and the 7 plug. I then was referred to the RV place that had installed a Hayes Brake Control Box in 2009 and today the RV place put in a new Hayes Brake Control Box. To tell you the truth, since I returned from the RV place, I have not ventured to the garage as yet to see if the brake lights are on.