Two childhood friends John and James shared the same house when they started working.
John was married and James was not.
After work John went to night school every day with the idea of bettering his job.
James was lazy and just stayed home watching TV.
Every morning John bullies James by asking questions about what he learned at night school. James never knew the answers and John kept bullying him.
One day before John asked the question, James surprised John and asked him who David was.
John had no clue and started thinking for a long time and
finally said, I really don't know who David is.
James said, oh is that so?
David is the Guy who sleeps with your wife when you go to night school.