The chord that is made purely of the notes C#, G and another C# is used frequently 
throughout this song.
I can't find a name for it, but it is close to Dbb5, which also contains an F.
The chord is denoted as Dbb5 but can be played like this without the F.
e------ | 
b------ | 
g-6---- | 
d-5---- | 
a-4---- | 
e------ | 



G5                  Dbb5
 I was thinking of sex and

         G5              Eb5 D5
All the nasty things we do

G5                  Dbb5
 I was thinking of love and

         G5          Dbb5
How you got none in you

G5          Dbb5       G5          Eb5  D5
 I piss my pants in an expensive suite

G5            Dbb5            G5          Dbb5
 I can keep my hat on in the worstest hurricane (make it rain)

(Pre-Chorus)

G5              Bb5
Hold me, I get lonely

        C5          D5
I can only wait so long

    D5         G5
I'm losing my mind,

Bb5            D5
Losing my mind

(CHORUS)

G5
Keep the flowers

Bb5                  G5
I'll just give 'em back

            Eb5            Bb5                D5
'Cause the only way to my heart is with an axe

G5
Keep the flowers

Bb5                  G5
I'll just give 'em back

            Eb5            Bb5                D5
'Cause the only way to my heart is with an axe


( G5 , Dbb5, G5 , Eb5 , D5 , G5 , Dbb5, G5 , Dbb5)


G5        Dbb5           G5
 A cup of coffee before bed

            Eb5  D5
So I dream fast

G5             Dbb5
 I stoled your car that

  G5         Dbb5
I purposely crashed


(Pre-Chorus)

(CHORUS)

Eb5
Let me let you know
G5
Let me let you know
D5
Let me let you know
Eb5
Yeah yeah yeah yeah

G5
Let me let you know
D5
Let me let you know
Eb5
Let me let you know
G5
Yeah yeah yeah yeah

D5
Let me let you know
Eb5
Let me let you know
G5
Let me let you know
D5
Let me let you know
Eb5
Let me let you know
G5 , D5 , Eb5

(Pre-chorus)
(Chorus)

Use verse progression for first set of 'let me let you know's following final chorus:
( G5 , Dbb5, G5 , Eb5 , D5 , G5 , Dbb5, G5 , Dbb5)

End with alternating between Gm and Dbb5.