A woman is constantly seeing the same man in an elevator every Friday at 3:00

She gets off on the 3rd floor and he always goes to the 5th. Finally one day she says “it always see you here,

 I get off on the third floor and give blood “ bragging she says”my blood is rare so they give me $50 a week.”

 The man smiles and says well I get off at the sperm bank where my donation gives me $100 a week” The next Friday the man holds the elevator for the lady and says “3rd floor right?” She shakes her head no and with puffy cheeks she mumbles “fiiffth”