The Security Guard

Passing an office building one Sunday, a girl saw a sign that
said, "Press bell for security guard."

She did so, and after several minutes she heard the guard
clomping down the stairs. She watched him shut down the alarm system,
put three different keys in three different locks, and finally open the
door.

"Well," the security guard said to the girl, "what do you want?"

She looked at him curiously. "I just wondered why you couldn't ring it
yourself."