It's relative to whether gravity is going from your head to your feet (+1g) or you are floating in space (0g) or hanging upside down by your ankles (-1g).
S&L inverted flight is only possible in a toy helicopter, as real ones don't have the capacity for negative collective pitch (apart from a couple of navy machines, and only to hold them on the heaving deck). And the fuselage is designed to hang under the rotor system, not stand inverted on it.
