"Mermaid" joke

There's these three guys and they're out having a relaxing day fishing.
Out of the blue, they catch a mermaid who begs to be set free in return for
granting each of them a wish. Now one of the guys just doesn't believe it,
and says:
"Ok, if you can really grant wishes, than double my I.Q."
The mermaid says: "Done."
Suddenly, the guy starts reciting Shakespeare flawlessly and analyzing it
with extreme insight. The second guy is so amazed he says to the mermaid:
"Triple my I.Q.." The mermaid says: "Done."
The guy starts to spout out all the mathematical solutions to problems that
have been stumping all the scientists of varying fields: physics, chemistry,
etc.
The last guy is so enthralled with the changes in his friends, that he says to
the mermaid: "Quintuple my I.Q." The mermaid looks at him and says: "You
know, I normally don't try to change people's minds when they make a wish,
but I really wish you'd reconsider." The guy says: "Nope, I want you to
increase my I.Q. times five, and if you don't do it, I won't set you free."
"Please," says the mermaid "You don't know what you're asking...it'll
change your entire view on the universe...won't you ask for something
else...a million dollars, anything?" But no matter what the mermaid said, the
guy insisted on having his I.Q. increased by five times it's usual power. So
the mermaid sighed and said: "Done."
And he became a woman.