Weird tapping sound when car is off

I got a weird one for you. When I turn my car off after driving for a bit, every 5-10 seconds it sounds like someone taps the bottom of the car with their fingertip in random spots. I figure it's just the metal and such cooling down after being at operating temp, but it seems kinda loud for that imo. Just curious as to what it could be. Only seems to last for a few minutes