right so I was watching the new Kevin James film 'Here Comes The Boom' and there's a
scene in it where Henry Winkler gets a guitar and does an acoustic version of the song. I
instantly wanted to learn it but couldn't find it on this website, so I watched ad 
listened carefully and now think I might have it! it's my first tab I've posted on this website
so some feedback would be appreciated:)

he doesn't play the whole song, only a wee bit of it, so this is all I could get.
you can find it on YouTube to listen to for the timing.

           E5
Boom. Here comes the boom.
                    G5                       A5
Ready or not, here come the boys from the south.
E5.           G5          A5
It's alright, it's alright.

play last chord once and pause for 4 beats.

    E5
Boom. Here comes the boom.
            G5                 A5
Ready or not, here come the boys from the south.
         E5
Boom. Here comes the boom.
                       G5       A5
Ready or not, how ya like me now?

E5     G5    E5    G5     E5    G5     E5    G5
 /     /     /     /     /     /     /     /     /     /     /     /     /

and then it breaks in to the original version.
I'm pretty sure these chords could be used with distortion to play the original, but
this is just the acoustic here.

hope I was helpful, and again please leave feedback:)

and I hope the positioning doesn't get too fucked up when this changes font...