The title pretty much says it all. This episode is out of order, because Mark was drunk enough to have forgotten that he recorded it altogether. Mark was also fairly drunk when he edited this episode, and when he wrote this thing you're reading right now. The point is he can't really remember what happened this episode, but it might've been kind of funny.
The one thing is it takes place before Henry went on his first date with the girl he's now been on several more dates with, and has referred to it on an earlier episode.