In floor 347, a glass cup sits in the center of the room. No windows, plain walls, and a tiled floor. You stride up to the cup and see a clear liquid in it. You think to yourself that you're extremely parched after climbing all those stairs. You pick the cup up and take a small sip to test the taste. Before you know what's going on, the cup and contents disappear into thin air. Confused, you back away slowly towards the stairs you entered from. But when you turn around, all you see is a blank wall. You claw at the walls frantically to try and find out what's going on, to see if someone's playing a prank on you, screaming at nothing. Eventually, you give up and slink down into a fetal position. Your eyes close, and you find yourself in a perfectly normal room with windows and paintings and furniture and such, and you briskly walk to the next stairway before anything else happens.
Don't drink strange liquids, kids.