The Big Bang TheorySeries 2 Episode 12: The Killer Robot Instability
When Kripke challenges them to a robot duel, Sheldon jumps at the idea. The guys are all excited about building their `killer' robot, named Monte, but the duel goes awry and Monte is the causality. Elsewhere, Penny finally tells Wolowitz what she thinks of his crude behaviour toward women and he is devastated, and Leonard convinces her to go and apologise.
- Original air date