it is ad idiom. it meas that it is in the past and you let it go. Similar phrases are "forgive and forget" and "letting it go". It basically means that a person did something that they failed to do.
USA
Let It Slide was created in 2006.
Let Your Backbone Slide was created in 1989.
latin
The Bible
from joey in friends
stop
1820-30
facebook entry
in concord and lexington.
from girls ...to hissy...
The phrase "over the pond" is commonly used to refer to crossing the Atlantic Ocean, particularly from the United Kingdom to the United States. It is a colloquial way to indicate travel between the two countries, given the large body of water that separates them.