This company hires a new guy and he's supposed to start work on a Monday, but instead of showing up he calls his boss and says, "I'm sick."
His boss tells him not to worry and lets him have the day off.
The guy then shows up at work on Tuesday morning and works throughout the week, greatly impressing everyone with his diligence and ability.
The next Monday he once again calls his boss and says, "I'm sick."
The boss reluctantly excuses him again, but takes note that this is the second Monday in a row that he hasn't been in.
Once again the man shows up on Tuesday morning and works furiously throughout the week.
The following Monday he calls his boss again and says, "I'm sick."
His boss excuses him, but decides to castigate the man on Tuesday.
Tuesday comes and as soon as the guy shows up, his boss calls him into his office.
"What's happening?" asks the boss. "I can see you're a hard worker, but you've only been here three weeks and you've called in sick every Monday."
The bloke replies, "Well, my sister is in a bad marriage and I go over to console her every Monday morning before work. One thing leads to another and we end up having sex all day long."
"Your sister!" says the boss, "That's disgusting!"
The man replies, "I told you I was sick."