Season 2, Episode 3 - The Barbarian Sublimation
Aired October 6, 2008
When Penny feels down on her luck, Sheldon introduces her to online gaming. After Penny finds herself addicted to the virtual world, Sheldon regrets the monster he's created.
Season 9, Episode 12 - The Sales Call Sublimation
Aired January 7, 2016
Penny gets more than she bargained for when Leonard agrees to meet with a psychiatrist
on her behalf. Also, Sheldon and Koothrappali collaborate on an astronomical discovery, and Wolowitz and Bernadette can't believe what they are feeling after Stuart moves out.