Rules of Engagement Season 4 Episode 13 (Rules of Engagement s04e13) with title “They Do?” airs on Monday, May 24th 2010 at 08:30 pm via CBS.
Here is summary for Rules of Engagement Season 4 Episode 13 :

In this finale episode, Adam and also Jennifer plan to get married in secret, but events threaten their hopes. Meanwhile, to divert Russell and Timmy, Adam tells them he’s having an intervention for Jeff, who Adam says has a drinking problem.

Few hours after original series aired on TV, online streaming video for Rules of Engagement Season 4 Episode 13 usually available on Net and of course, if video available, as soon as possible will show you where you can watch this episode for free.