Point of Impact
In slang terms its that moment when a dude enters someones ass hole with their dick, this can and is usually proceeded by some preparatory light prodding and always results in loud noises of some kind. Essentially the point of impact is when somebody just begins getting fucked in the ass.
Alex screamed as his partner Ned passed the point of impact, he could feel his ass hole loosen and the blood vessels shattering. It was the best feeling he had ever experienced.