Eggs can sit. As for how long after it has been in the nest, if being sat on by a broody, tops 2 days IF you have something against eating devloping embryos... shoot.. look up balut, and that's eatable. Eggs if not dirtied or cracked, are essentially sterile inside. Contamination generally occurs when they are washed in water cooler than the egg and forces bacteria though the shell as the bloom is being washed off. In healthy birds, no bacteria should be found in the egg.
I have eggs in my room that have been here for at least 5 years if not longer. They just dry out. I have no plans on eating them though.
Now, if you crack and egg and you have to open all the doors and windows of the house, don't eat it. But if it looks fine, go right ahead.