Dean Pelton lets two designers test their new social networking application at Greendale, leading to a war among the students; Professor Hickey decides to go underground until the battle ends.

The Pearsons come together to celebrate Kate and Toby’s wedding. Wedding planners Kevin and Randall struggle to pull off the big day. Kate is flooded with memories of Jack. Deja…

Kate and Toby go to Las Vegas for their bachelor/bachelorette parties. Meanwhile, Jack and Rebecca celebrate their wedding anniversary.

Rebecca and Jack get into an argument about starting a family. The family backstory behind the long line of love for the Pittsburgh Steelers is revealed. After accepting his part…