Wierdiest thing ever! Help anyone?

[twack]

Hey i was coming home today from visiting my mom (in my jeep) and i park in front of the garage door and then i walk in to my house (never went into the garage or opened it). A couple of minutes of being inside i hear like a loud car outside, so i ask my gf to look who was parked outside she said no one and then she was leaving to go to the bar and runs back up and was like it in the garage. i went out there and i heard my car running then i asked my gf to hit the opener and then the noise stopped. it opened and there was smoke everywhere and the car had been on. i cant figure it out. creeps the hell out of me. anyone ever heard of this or got any ideas seriously im at a loss how my car started and ran in a locked garage with no doors or windows and no keys and it was in the off position!!!