A blonde, redhead, and a brunette were riding in an elevator when they reach the top floor and the doors open they all notice a small spot of fluid on the floor.
The redhead puts her finger in it and feels it. "It feels like semen."
The brunette puts her finger in it and smells it. "It smells like semen."
The blonde puts her finger in it and tastes it. " Its not from anyone on this floor."