From the episode called "The Zazzy Substitution"
Raj: I printed out a pdf to read on the potty. Penny: Hey, look it's Shamy Wolowitz: And someday when you have varicose veins, I'll show you how to massage them. Leonard: Oh no, it's John and Yoko. Wolowitz: More like Yoko and Yoko. Wolowitz: Women, can't live with them, can't successfully refute their hypothesis Shelton: Raj, Howard, I'd like you to meet Dr. Robert Oppenheimer. Shelton: Here's your cat, and here's your $20