The Herb Garden Germination (2011)

Penny spreads a rumor that Bernadette is thinking of breaking up with Howard. After the rumor finally reaches Priya, she informs Leonard that Raj has a crush on Bernadette and even writes poems about her. When Raj hears the rumor from Priya, he gets excited, as he could finally have his own shot with Bernadette. Howard is completely unaware of all this and plans to ask Bernadette to marry him. The others try to stop him from asking, as they believe that he will be blindsided when Bernadette rejects him, with Raj being the only one that selfishly encourages Howard to go through with his plan. When having dinner one night, Howard pulls out the proposal ring, as he can't imagine a better time to ask her than with all of his friends around. Despite the protest of the others, he gets on his knees and starts to talk. At that moment, Bernadette cuts him off in what appears to be a rejection, however she actually accepts his marriage proposal, completely devastating Raj at the same time.

The rumor about Bernadette breaking up with Howard motivates Amy and Sheldon to conduct an experiment in which they concurrently spread two false rumors: a "tantalizing" one and a "non-tantalizing" one to see which rumor gets back to them first. Amy starts both rumors by informing Penny and, as expected, the rumor about the two having sex reaches the entire group in under 24 hours while the other one isn't mentioned again. When Howard's proposal distracts the group from the rumor, they decide to start over with their experiment. Amy visits Penny again and tells her that she is getting orthotics and that she is pregnant with Sheldon's baby. Moments later, Leonard meets Amy in the hall after he receives a text message from Penny, informing him about the false pregnancy. He confronts Amy, who, in return, just wonders if there "is anything on there about orthotics?".

Physicist Brian Greene makes a cameo appearance at the beginning of this episode, featuring his book The Hidden Reality.

Recurring character: Aarti Mann as Priya Koothrappali.

Title reference: The mundane false rumor that is part of Amy and Sheldon's experiment.