Finally an answer to the question..
Once upon a time all dogs were invited to
a party. When they arrived at the party
they were required to leave their
butts at the door. All the dogs hung them
on hooks by the door.
The party went on and the dogs were
having a great time. All of a sudden
a fire broke out. The dogs raced to
the door and grabbed whichever butt
they could grab first.
In an effort to find their own butt.
that is why, to this very day,
dogs sniff each other's butts!!!!