I came across this when doing a Google search for the real Return of the Jedi script. It made me roll on the floor laughing!

Please note, there are some vulgar words (like the F word and a couple others) so be warned...

Alternative ROTJ script

Quotage (with some bad words edited out):

C3PO and R2D2 enter and show JABBA a message from MARK
HAMILL.

MARK HAMILL
My costume makes me look kind of
like a priest.

BIB FORTUNA
This guy isn't a Jedi. Notice how I
speak Huttese to the largely
English- speaking droids yet I speak
English to Jabba?

The droids are taken away to act foppish and comical. We see
droids being subjected to torture. Seriously.

JABBA is being entertained by various aliens including a
hot green chick. Suddenly, a large number of very obviously
CGI aliens partake in an overly long dance sequence. STAR
WARS FANS hold their heads in their hands and begin to cry.

BOBA FETT
I'm cool, by the way. See
these chicks hanging all over me?
I rule.

A resuce attempt begins taking place.

BILLY DEE WILLIAMS
I will now pull down my mask. This
serves no actual purpose here in
Jabba's palace, and I am doing it
solely for the audience. How long
have I been here anyway? Couldn't I
just have shot JABBA by now?

CARRIE FISHER rescues HARRISON. She then gets CAUGHT and put
into a small gold bikini. STAR WARS FANS have now been
fueled for twelve thousand more fantasies.

MARK arrives.

MARK HAMILL
Whoa, Carrie is hot.

ALEC GUINESS
Oh man, you're gonna be so pissed
in a little while.

EXT. DEGOBAH

MARK greets YODA.

YODA
Frank Oz seems to have forgotten
how to do my voice. I now sound like
Miss Piggy if she were a
chainsmoking drunk.

MARK HAMILL
I'm here to complete my training.

YODA
Oh. Uh, I dunno I'm kind of tired. I
guess you're done. Have fun.

MARK HAMILL
Then I am a Jedi.

YODA
Ha ha, yeah, sure, whatever. You
have to fight Vader first.

MARK HAMILL
Er, but, last time you saw me you
told me I wasn't ready to face him.
And I haven't trained more since
then. So why am I ready to face him
now?

More...

Everyone is capured by EWOKS! The EWOKS think C3PO is a
god.

C3PO
I'd love to use this to our groups
advantage, but apparently I've been
specifically programmed not to
impersonate deities. This is a high
priority in my programming. God-
impersonating must be a serious
problem with protocol droids.
(pause)
I'll do it anyway, though. Just
don't ask me to impersonate clowns,
anchormen, or truckers. That is
strictly forbidden in my
programming.

And one more...

EMPEROR
You know.. I'm the one who gave the
rebels the location of the
generator.

MARK HAMILL
Er, you gave them the location of
the ACTUAL generator? Not some
decoy? I mean, isn't that pretty
stupid?

EMPEROR
Quiet! Don't sass your elders, boy!

DARTH VADER
Hey, anyone ever notice how I
sometimes talk and breathe at the
same time? Isn't that weird?

Read the rest here (beware of some cussing).