Sorry the lyrics are probably wrong because I couldn't find them anywhere!
If you tune your guitar down one whole step I think it's in the same key that they sing it in

E A E   
E A E 


E          A             
  Hey girl I'm waiting on ya
E   A          
  I'm waiting on ya
E             A                B
  Come on and let me sneak you out
E            A
  And have a celebration
E   A
  A celebration
E           A              B
  The music up the windows down


C#m    A          E            B
  Yeah, we'll be doing what we do
        C#m                A
Just pretending that we're cool
       B
And we know it's true
C#m    A          E            A
  Yeah, we'll be doing what we do
         C#m              A
Just pretending that we're cool
     B
So tonight


         E                               A   B   E
Let's go crazy crazy crazy crazy 'til we see the sun
  E                             A    B    E
I know we only met but let's pretend it's love
    E                          A B  C#m
And never never never stop for anyone
E             C#m    
Tonight let's get some
A
 And live while we're young


E    A    B
C#m   A   E
E    A    B
   C#m       A   
Tonight let's get some

And live while we're young


E  A  E   


E          A             
  Hey girl it's now or never
E   A          
  now or never
E             A               B
  Don't over think just let it go
E            A
  And if we get together
E   A
  get together
E           A                       B
  Don't let the pictures leave your phone


C#m    A          E            A
  Yeah, we'll be doing what we do
         C#m              A
Just pretending that we're cool
     B
So tonight


         E                               A   B   E
Let's go crazy crazy crazy crazy 'til we see the sun
  E                             A    B    E
I know we only met but let's pretend it's love
    E                          A B  C#m
And never never never stop for anyone
E             C#m    
Tonight let's get some
A
 And live while we're young


E    A    B
C#m   A   E
E    A    B
   C#m       A   
Tonight let's get some

And live while we're young


E     B      C#m      A
    E       B        C#m      A
And girl  you and I      we're 'bout to make some memories
    E       B                       C#m      A
  Tonight   I wanna live while we're young   We

wanna live while we're young


         E                               A   B   E
Let's go crazy crazy crazy crazy 'til we see the sun
  E                             A    B    E
I know we only met but let's pretend it's love
    E                          A B  C#m
And never never never stop for anyone
E             C#m    
Tonight let's get some
A
 And live while we're young

E                               A   B   E
crazy crazy crazy crazy 'til we see the sun
  E                             A    B    E
I know we only met but let's pretend it's love
    E                          A B  C#m
And never never never stop for anyone
E             C#m    
Tonight let's get some
A
 And live while we're young

E    A    B
C#m   A   E
E    A    B
   C#m       A   
Tonight let's get some

And live while we're young