Wrong Number.
A man joined a big Multi National Company as a trainee. On his first
day he dialed the cafeteria and shouted into the phone, "Get
me a coffee quickly!" The voice from the other side responded,
"You fool you've dialed the wrong extension! Do you know who
you're talking to, dumbo?" "No", replied the trainee.
"It's the Managing Director of the company, you fool!" The
man shouted back, "And do you know who YOU are talking to, you
old Bastard?" "No.", replied the Managing Director.
"Good!", replied the trainee and put down the phone!