The Big Bang Theory season 9
Howard and Raj plan a surprise bachelor party for Leonard in The Big Bang Theory season 9 episode 3CBS

The gang kidnaps Leonard for a surprise bachelor party in Mexico, but things do not go their way in The Big Bang Theory season 9's third episode. On the other hand, the girls have their own party where they force Penny to come clean to her family about her wedding with Leonard, while Amy thinks of changing her wardrobe to get over her breakup with Sheldon.

Episode 3 is titled, The Bachelor Party Corrosion, which will air on Monday, 5 October at 8pm EST on CBS Network. The official synopsis reads as follows:

The guys' science skills are put to the test when they get a flat tire during Leonard's bachelor party weekend in Mexico. Also, the girls force Penny to finally tell her family that she eloped with Leonard, on The Big Bang Theory.

According to a new report, Amy and Bernadette throw a mini bachelorette party for Penny, who calls her father and finally reveals to him that she got married in Vegas. Besides, Amy who wanted to change her wardrobe, gets her ears pierced instead. The genius gang whisks Leonard to Mexico for a bachelor party, where they end up with a flat tire and struggle to change it.

A new promo shows an excited Sheldon in a bus, and we hear Amy telling Penny and Bernadatte, "I was thinking of changing my wardrobe," to which the girls reply in unison, "Your glasses, your shoes, your hair."