This isn't really an opener but I think it might be my favorite number close I ever got.
Walked into an elevator, I hold the door for an HB 9. Our convo went like this:
Flint: What floor?
HB: (Her floor)
Flint: (Presses button) That'll be $5.
HB: (Laughs) Sorry I don't have any cash on me, do you take debit?
Flint: No but I'll take your number.
Idk if that counts as an opening but that's my favorite elevator routine.