You may have at some time heard me refer to my residence as "The Penthouse". It is not, I assure you, a penthouse in any way, shape, or form. The origin of this colloquialism goes back to my previous residence on 140th Street. In that building, I lived on the topmost floor and, when my roommates and I were moving in, we saw that the previous tenants had put a sign on the front door of the apartment (7G) that read "Penthouse G".
Naturally, we decided to keep this sign on the door and, before long, we started referring to our apartment as The Penthouse (so instead of "are you heading home?" we would ask "are you headed back to The Penthouse"). After leaving that residence, some of our cohort remained together in our next apartment so the Penthouse name (and really almost a brand, at that point) followed us to our new residence (which is even less of a penthouse since it's not even on the top floor of the building), which we now refer to as The Penthouse 2, or P2 for short.