When one person is attempting to reference a memorable experience with another individual the other doesn't always remember the event. In order to avoid an awkward episode of the story teller trying to jar the memory of the other party, one will "pretember" the event. They will pretend to remember so that the story may go on.
Mike: "Hey Joe, do you remember that time as kids when we went to the neighbor's house and snooped around?" Joe: "No, Mike, I don't remember that." Joe: "Really? It was that yellow house next door and it was raining that day." At this point Mike just wants Joe to get on with the story, so he implements his pretembering. Mike: "Oh yeah! I pretember that!"
by p112812 March 23, 2011