A psychiatrist wanted to know how many of his patients have been cured of madness

A psychiatrist wanted to know
how many of his patients have
been cured of madness, so he
assembled them in a classroom
and drew a big door on d
board. He den told d class that if anyone can open d door on d
board, that person will receive
a gift of 20,000 cash and will
be free to go home. On hearing
this, they all rushed to d board
to open d door, except one young man who remained in his
seat at d back smiling. The
psychiatrist, with joy and
excitement on his face seeing
that somebody has been cured
of madness, went to him and asked, why didn't u join ur
mates to open d door?The
young man replied, no mind
those mad people, they don't
know that the key is in my
pocket.