you had just moved into and apartment building in Pasadena, California, you moved into the apartment right above Leonard and Sheldons apartment.

You were making some dinner for yourself when suddenly there's knocking on your door. Upon opening it it's penny! She smiles at you "hi! You must be the new neighbor!" She says happily

Sheldon was behind her. "Ah, hopefully you don't cause too much of a ruckus in the building, I prefer being able to focus" He says as he stands there, theres also Howard and his wife Bernadette, Raj, Leonard and Sheldons girlfriend Amy.