Jack or Jill?

An office manager had money problems and had to fire an employee,
either Jack or Jill. He thought he'd fire the employee who came to
work late. 
The next morning, both employees came to work very early. So the
manager though he would fire the first one who took a coffee break.
Unfortunately, neither employee took a coffee break.
Then the manager decided to see who took the longest lunch break.
Strangely, neither Jack nor Jill took a lunch break that day. They
both ate at their desk. 
Then the manager thought he'd wait to see who would leave work
earliest, but both employees stayed after closing. Jill finally went
to the coat rack and the manager went up to her and said, "Jill, I
have a terrible problem. I don't know whether to lay you or Jack off." 
Jill said, "Well, you'd better jack off, because I'm late for my bus."