After Sheldon is not invited a weekend physicssymposium at one of Richard Feynman’s former homes, he is very depressed at his Date Night with Amy. They discuss how they have been excluded from things in their lives like when from the forts built by his brother and sister when he was growing up. Amy can't get him invited to the symposium, but she suggests that together they could build their own fort. The fort is byult of blankets and sheets in their living area with Christmas lights hanging from their ceiling. After roughing it by sitting on the floor, they both think that it is a really amazing fort. Shamy conducte dtheir first annual greatest fort ever contest. Their fort (Fort Cozy McBlanket) beats Fort Knox. After Amy's alarm goes off, Sheldon isn't ready to stop and suggests that they extend the Date Night parameters. Amy suggests their first sleepover. Sheldon is fine as long as it is G-rated, though Amy is pushing for PG. Does she need pajamas or a toothbrush? Amy had previously hid a set under the couchcushion in case she ever spent the night. And there might be another set in Sheldon's bedroom. When Leonard returns home and finds the fort built using his sheets. Sheldon wants Leonard to ask to come in just so he can say no. Leonard agrees and asks to come in. Luckily, Sheldon thinks it's such a great fort that he can't say no, though he won't let Leonard sit in his spot.
The initial first round candidates in the first annual best fort ever contest were Fort Cozy McBlanket, Fort Bragg, Fort Benning, Fort Sumter, Fort Ticonderoga, Fort Irwin, Fort Wayne and Fort Knox. We all know who won.
Within the confines of the fort, Sheldon and Amy spend their first night together, though G-rated.