A struggling artist Hee-do is offered a million dollar to bet his life if he loses a game against a rich old man named No-shik who is dying from a terminal disease. The game is to dial any random number and tell whether it would be male or female who takes the call before the phone gets answered. Hee-do calls “Female” and No-shik “Male.” It turns out the call-answerer is a drag queen and Hee-do loses. After a month of a brain operation, No-shik wakes up in Hee-do’s body and Hee-do does in No-shik’s. With Hee-do’s young healthy body, No-shik is now the man of health and wealth, let alone romance with the clueless Hee-do’s fiancé. Meanwhile, No-shik’s ex-wife convinces the frustrated Hee-do to help her lay out a scheme to revenge upon No-shik by revealing the truth. However, the woman is found dead not long after in No-shik’s office building. Hee-do comes to another showdown with No-shik and makes the second bet that could return his lost body if he wins and could lose his memories about his fiancé to No-shik if he fails. Each calls out random numbers and waits for the voice to be heard.
the "bad guy" lost the bet so he asked
to do the surgery where the memory of
the young guy is put into his body (and
therefore the original guy's memory
is erased and he dies as an old man
and so that's him (the bad guy) at
the end just with the memory of the
original guy..but he only found out
he's his son before the operation
so he didn't have a chance to
rethink it
......so in a way it's kinda the
same thing as switching back the brains
only their personalities stay the same
which explains how he only wants to
sleep and smokes in the same way as that
guy.
..OR..they did switch back...but he
continues to smoke because his body got
used to it..altho we haven't seen
the guy smoke before in the film he may
have already smoked before...