WTF Happened to my car?

So I'm sitting in my room and I hear a horn blaring. Its like someone is just holding their had on a horn and not letting go. My dad was in the bathroom and says its one of our cars outside I told him it was outfront he said its outback its one of ours. So i walk out to fine my car sitting there with the tail lights and corner lights on and horn blaring. My light switch was off i hit the steering wheel and nothing tried to start it and nothing. So i figured pull the battery. As I was walking away the horn just stops but the lights stayed on. I ended up pulling the batery to get the lights to go off anybody ever have this happen? Or know WTH is wrong with it?

Don't have the key fob things. And as far as i know it doesn't have an alarm. It has keyless entry but I thought it should have a light or say theft in the instrament panel if it has an alarm maybe I'm wrong?

LOL yeah its a Mystery car thats for damn sure. Think I might have found the problem. I remembered the trunk leaked over the keyless entry box and it got wet before so I just ran out and checked it my amp was in laying in the spare tire hole with some water under the one side hope it dries up and will be fine. But when i turned the keyless entry box over water poured out of it. I'm hoping thats the problem.

I have planed to "fix" the trunk it leakes bad like the whole channel is ****ed. So I was thinking about cleaning it up cause it looks like somebody tried to ghetto fix it with something. Probably damn weather stripping glue ya know the black stuff (have found it other places on my car ) and fiberglass it with bondo fiberglass and when I get the ass end painted have them hit that too

Also beings I had the trunk riped apart when i did the suspension I left all the pieces out till i get the leaking problem fixed other wise my amp would be mounted. And i woudl have them molded pieces re covered