When I was a teenager (15 years ago
), my parents took my car ('84 Accord beater) to the grocery store and a four-pack of butter sticks slid out of one of the bags and hid in the trunk. So then I go work for the rest of the day in the summer GA heat and of course it melts out and soaks into the trunk carpet.
By the end of the next day I know sumpin' ain't riaaaght, and found the problem.
I don't remember doing much of anything besides removing the now-empty box of butter and the smell died down eventually.