The Big Bang Theory Recap with Spoilers – "The Platonic Permutation"

The episode opens with Raj showing off the "buttonless" Siri feature on his iPhone. The feature is keyed to Raj's voice, but Howard has an accurate enough Raj impersonation that he gets Siri to look up pictures of "naked grandma butts" on Raj's phone. Sheldon comes in and tries to convince one of his friends to join him in his annual tradition of going to the aquarium cafeteria for Thanksgiving. Unfortunately, Sheldon can't find any takers as Leonard and Penny are hosting their first Thanksgiving dinner as a married couple and Raj and Bernadette are volunteering at soup kitchen.

With no one to go with, Sheldon offers both aquarium tickets to Amy. Amy can tell Sheldon wants to go to the aquarium so she offers to go with him as friends.

Howard, Raj, Emily and Bernadette arrive at the soup kitchen, but the manager turns them away as they have too many volunteers. Howard (who didn't want to come in the first place) gets all smug about not volunteering, but the soup kitchen manager changes his mind and asks them to stay and help.

As they start preparing their first Thanksgiving dinner together as a married couple, Leonard asks Penny to pull up the recipes on his iPad. Leonard tells Penny that the code for the iPad is his birthday, but Penny can't seem to unlock the iPad. After Leonard correctly puts the code in, he realizes that Penny doesn't know what his birthday is.

Amy picks Sheldon up to go to the aquarium. Sheldon pulls out a list of acceptable conversation topics to keep things from getting awkward and successfully engages his ex-girlfriend in a harmless round of small talk. Amy eventually gets sick of the small talk and tells Sheldon to say whatever's on his mind, which leads Sheldon to immediately ask if she's had sex with any of the other men she's seeing.

The soup manager puts Howard, Raj, Emily and Bernadette to work cleaning dishes. Howard's upset that he's not actually on the soup line, as he hoped that a young orphan would walk up to him and start quoting Oliver Twist.

Leonard flaunts how much he knows about Penny, but he slips up when he mentions that Penny hated his Valentine's Day present (lingerie that made her look like a slutty carrot). Penny realizes that Leonard's been reading her private journal.

Back at the soup kitchen, Howard starts complaining when he realizes he's only been there for twenty minutes. Raj tells Howard to use the dish washing as an opportunity to meditate, which Howard takes to heart. However, Bernadette, Emily and Raj quickly abandon Howard when an opportunity arises to serve on the soup line.

Penny's still upset about Leonard reading her journal (he said it was an accident), so Leonard tries making it up to her by reading excerpts of his online journal out loud. When Leonard starts reading the excerpt from the day he met Penny, she sees through his attempt at buttering her up and demands to see his most recent entry, which is a post about how excited he is for the new Star Wars movie.

Sheldon senses that he's made things awkward, but Amy says that if they're friends, they should be able to talk about anything. Amy gives Sheldon the okay to ask a series of questions about Amy's dating life, which Amy answers honestly. Amy asks if Sheldon's doing okay and then tells him that she wants him to be happy.

While washing dishes, Howard meets Elon Musk, the founder of Tesla and SpaceX. After they hit it off, Musk mentions that his company is always looking for qualified engineers and the two share a partially eaten piece of pumpkin pie. Looks like volunteering paid off for Howard, after all.

At the aquarium, Sheldon gets upset that they gave a baby a pilgrim hat instead of him, to which Amy replies that it wouldn't be a holiday without Sheldon getting upset over a baby. Sheldon explains the rules to "Friend, Food or Fight", (it's basically "Kiss, Marry, Kill" only with sea creatures) and the two start to play. After a couple of rounds of "Friend, Food or Fight", Amy says she misses "this", but Sheldon doesn't know how she could miss a game she's never played before.

Leonard dresses up in Penny's lingerie in one final attempt to patch things up with his wife. He offers to let Penny take a "shame photo" and post it online, but Penny doesn't want anyone (including herself) to see Leonard in lingerie. Leonard tries to get a little frisky with Penny, just as their friends walk in for dinner. Looks like everyone got to see Leonard in lingerie after all.

After dinner, Sheldon helps Leonard and Penny clean up and tells them that he's glad him and Amy are now friends. Amy calls Sheldon on the way home from her mother's house and says she's ready to be his girlfriend again. However, Sheldon turns her down, as getting over Amy was one of the hardest things he's ever had to do and he doesn't want to go through that experience again. The episode ends with Amy agreeing to remain friends with Sheldon, although she's visibly upset by his rejection.