joke

Here is a clean joke I heard long time ago but it is still as fresh as ......

A young man  one day wrote to his father.  After opened this letter the father found out his son only wrote 3 sentences:
NO MON.
NO FUN
YOUR SON.
So the father wrote back to his son.  when the son opened it up, 3 sentences also:
TOO BAD,
SO SAD.
YOUR DAD.
Have a cheerful Monday.