The Job

"Can you start on Monday?" the man asked.
"Yes, of course."
It was a job she didn't want, but at least it paid well.
Monday came and she turned up at the building and knocked on the door.
"Who are you?" asked the man who'd asked if she could start on Monday as he opened the door.
"I'm here for the job."
"What job?"
"The job you offered me last week. You asked me if I could start on Monday."
"There's no job."
She walked away.
The man's twin appeared at the door.
"Who was that?" he asked his brother.
"Nobody."