Mail Slot
When the top of the crack of someone's huge ass can be seen because of low-waisted pants or shorts, and the gap is so wide or large that a parcel or large envelope could fit. Not to be confused with Coin Slot, a much smaller crack that accommodates change.
In the parking lot today at Wal-Mart I saw an enormous woman clammer off of her mobility scooter and load her groceries into her busted-ass minivan. She was showing off her Mail Slot when she slid the door closed to head back to the trailer park. The gap must have been four inches across.
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