Plotlines
Raj's inability to speak to women becomes an issue when his parents set him up with an Indian girl, in the hope of arranging a good marriage for him. When Penny uses the guys as guinea pigs for her bartending skills, Raj realizes that he can talk to women when he's drunk. He decides to set up the date and go to it drunk so that he'll be able to talk to her. Sheldon becomes enamored with her, because she looks like the character from a story his mother read him as a child. He ends up leaving the bar with her, though seems perplexed at the social faux pas he has committed (or why Raj is so angry).
The Episode's Science
Specific Gravity: While Penny is practicing mixing drinks, she gives Leonard a Tequila Sunrise, which Leonard describes as "a wonderful example of how liquids with different specific gravities interact in a cylindrical container." This is the physics explanation of how the different colored liquids, each of which has a different density.
Notable Quotes
Penny: Hi, guys. I need some guinea pigs.
Sheldon: Okay, there's a lab animal supply company in Racida you could try, but if your research is going to have human applications, may I suggest white mice instead? Their brain chemistry is far closer to ours.
Penny: I swear to God, Sheldon, one day I'm going to get the hang of talking to you.
Leonard: His mom's been saying that for years.
