This is what I play for the song. Enjoy. Tuning is standard EADG. Listen for timing and switching.

INTRO:
G|------------------------------------------------------------------|
D|------------------------------------------------------------------|
A|-3-1-3333333333333333---------------3333333333333333--------------|
E|---------------------333333333-1111-----------------333333333-111-|

VERSE: (All the small things...)
G|-------------------------------------|
D|-------------------------------------|
A|-33333333----------------------------| x4
E|---------33333333-11111111-33333333--|

Chorus: (Say it ain't so...)
G|--------------------------------------|
D|--------------------------------------|
A|-333333333--1010101010101010-88888888-|
E|--------------------------------------|

(Na na na na na...)                (X=10 Fret)
G|-------------------------------------------|
D|-55555555555555--1212121212121212-XXXXXXXX-|
A|-33333333333333--1010101010101010-88888888-|
E|-------------------------------------------|
 
G|-------------------------------------------|
D|-----------------1212121212121212-XXXXXXXX-|
A|-XXXXXXXXXXXXXX--1010101010101010-88888888-|
E|-88888888888888----------------------------|

INSTRUMENTAL
G|--------------------------------------------------------------|
D|--------------------------------------------------------------|
A|-3333333333333333---------------3333333333333333--------------|
E|-----------------333333333-1111-----------------333333333-111-|


VERSE: (Late night, come home...)
G|-------------------------------------|
D|-------------------------------------|
A|-33333333----------------------------| x2
E|---------33333333-11111111-33333333--|

CHORUS: (Say it ain't so...)
G|--------------------------------------|
D|--------------------------------------|
A|-333333333--1010101010101010-88888888-|
E|--------------------------------------|

(Na na na na na...)                (X=10 Fret)
G|-------------------------------------------|
D|-55555555555555--1212121212121212-XXXXXXXX-|
A|-33333333333333--1010101010101010-88888888-|
E|-------------------------------------------|
 
G|-------------------------------------------|
D|-----------------1212121212121212-XXXXXXXX-|
A|-XXXXXXXXXXXXXX--1010101010101010-88888888-|
E|-88888888888888----------------------------|

BRIDGE:  (~= Let ring)
G|-------------------|
D|-5~---10~---12~----|
A|-3~---8~----10~----|x3
E|-------------------|

G|-------------------------------------|
D|-55555555--XXXXXXXX-1212121212121212-|
A|-33333333--88888888-1010101010101010-|
E|-------------------------------------|


CHORUS: (Say it aint so...)
G|-------------------------------------------|
D|-----------------1212121212121212-XXXXXXXX-|
A|-XXXXXXXXXXXXXX--1010101010101010-88888888-|
E|-88888888888888----------------------------|


END: (The night will go on, the night will go on...) (P= Palm mute)
G|-----P-|       G|-----|
D|--10-P-|       D|-----|
A|--8--P-|x3     A|-10~-|
E|-----P-|       E|-8~--|

That's it! This song is really fun to play! Hope you enjoy!