Amy asks Sheldon if they are ever going to have an intimate relationship and then they end up playing private D&D.
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The girls join in on a game of Dungeons and Dragons for the very first time on The Big Bang Theory. "The Love Spell Potential" is the 23rd episode of the show's sixth season.
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The Big Bang Theory Season 6 Episode 23 Quotes

Leonard: Sometimes change is good. You were worried about Zachary Quinto being the new Spock, but you ended up liking him.
Sheldon: Leonard, please, every time the topic of change comes up you throw Zachary Quinto in my face. I'm upset the mailman has a new haircut -- Zachary Quinto. I'm upset daylight savings time started -- Zachary Quinto. I'm upset daylight savings time ended -- Zachary Quinto. I'm saying this for the last time. Zachary Quinto was a weird, wonderful, unrepeatable event, so stop using him against me.

We have a new rule if no one talks for three minutes you can just hang up. I'm so into her.

Raj