Howard and Raj arrive to kidnap Leonard ( and Sheldon as well)  for a surprise bachelor party weekend.

Howard reveals that they are heading to Mexico for a science themed trip.

Meanwhile, the girls have their own get together. Amy brings cookies in the shape of male genitalia.

Amy tells Penny and Bernadette that she was considering a change in wardrobe. She then reveals that she wants to pierce her ears. Penny insists that she do it herself.

They guys have to deal with a flat tire, and Howard has trouble trying to change it.

Amy and Bernadette are concerned that Penny hasn't told her parents yet that she and Leonard are married, but then Penny learns that Amy hasn't told her parents about her breakup with Sheldon.

Penny calls her father to tell him the news. He takes it surprisingly well, only because he's been keeping some news from Penny himself. he accidentally backed over her pet pig.

The guys continue to try to fix the tire, using scientific principles that all seem to fail. Then they accidentally light the entire van on fire.

The guys return disheveled from their trip, and Leonard and Penny talk about their weekends.