Outside lights come on by themselves

Exterior lights randomly turning on while car is off, doors are closed and locked, and keys are not in the car let alone the ignition, what can cause? I have had multiple times now where I or a family member or friend have gone outside to find my exterior lights on in my car, all doors are locked, its turned off and the keys are not even in the vehicle. They were off when I got out and locked it up and when in to where ever I was going work/ home etc. We have to turn it on and off and they will turn off. Usually I leave the switch on because they turn off when my car turns off usually but now I'm thinking I am going to have to remember to turn them on and off every time I drive. My battery died recently and now we think it may because this has been happening more than the 3 times I know about. What could be causing this to happen?