Sheldon: I came to go over your alibi for last night.
Leonard: What alibi?
Sheldon: You've asked me to lie on your behalf, and as you know, I am deeply uncomfortable with impromptu dishonest, so I've provided you with an iron clad alibi. You couldn't have spent last night with Priya, because you were with another woman.
Leonard: Oh, I'm so sure I'm going to regret this, but, who was I with?
Sheldon: The fun loving, and morally loose, Miss Maggie McGeary.
Leonard: Oh, God.
Sheldon: You met her at Pasadena's most popular Irish watering hole, Lucky Baldwin's, where Maggie spends her nights tending bar, with a head full of curls and a heart full of dreams.
Leonard: (reading a napkin that Sheldon gave to him) Leonard, call me if you're interested in coitus. Sincerely, Maggie McGeary.
Sheldon: And if anyone were to actually call that number they will hear this. (Robotic voice with an Irish accent from Sheldon's phone) Top of the morning to you. You've reached Maggie McGeary. Leave a message after the wee little beep.
Sheldon: It's pretty convincing, huh? And it wasn't even a real person. And here is the clincher. A lock of Maggie's flaming auburn hair.
Leonard: Where did you get that?
Sheldon: From an orang-u-tan in the primate lab.
Leonard: An orang-u-tan?
Sheldon: Well, no-one's going to run a DNA test on it, Leonard, honestly you over-think everything.