Each 2 measures has eighth notes like this:

EbEbEbEbEbEbAbAb|EbEbEbEbEbEbDbEb

Where I'm screaming Let's Party, don't go to the Ab or Db. In fact at any point they become optional depending on your mood.

So party time is in Eb.

Eb            
It's party time
Eb
It's party time
Eb
Gonna rock you now
Eb
Gonna show you how
Eb
Let's Party
Eb
Let's Party
Bb
Glad to see you all having fun
Ab
Look out now cuz here we come.

Cops come in
give em some gin
Knock down the door
Give em some more
Let's Party
Let's Party
Bring out the beer, bring out the wine
I like to party all the time

Livin in sin
Is where we begin
Lovin life
Makes it right
Let's Party
Let's Party
Don't you worry bout what you've done
Cuz Jesus loves you when you're having fun.