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------ | 



Gm                  Dbb5
 I was thinking of sex and

         Gm              Eb D7
All the nasty things we do

Gm                  Dbb5
 I was thinking of love and

         Gm          Dbb5
How you got none in you

Gm          Dbb5       Gm          Eb  D7
 I piss my pants in an expensive suite

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

(Pre-Chorus)

Gm              Bb
Hold me, I get lonely

        Cm          D
I can only wait so long

    D7         Gm
I'm losing my mind,

Bb            D7
Losing my mind

(CHORUS)

Gm
Keep the flowers

Bb                  Gm
I'll just give 'em back

            Eb            Bb                D7
'Cause the only way to my heart is with an axe

Gm
Keep the flowers

Bb                  Gm
I'll just give 'em back

            Eb            Bb                D7
'Cause the only way to my heart is with an axe


( Gm , Dbb5, Gm , Eb , D7 , Gm , Dbb5, Gm , Dbb5)


Gm        Dbb5           Gm
 A cup of coffee before bed

            Eb  D7
So I dream fast

Gm             Dbb5
 I stoled your car that

  Gm         Dbb5
I purposely crashed


(Pre-Chorus)

(CHORUS)

Eb
Let me let you know
Gm
Let me let you know
D7
Let me let you know
Eb
Yeah yeah yeah yeah

Gm
Let me let you know
D7
Let me let you know
Eb
Let me let you know
Gm
Yeah yeah yeah yeah

D7
Let me let you know
Eb
Let me let you know
Gm
Let me let you know
D7
Let me let you know
Eb
Let me let you know
Gm , D7 , Eb

(Pre-chorus)
(Chorus)

Use verse progression for first set of 'let me let you know's following final chorus:
( Gm , Dbb5, Gm , Eb , D7 , Gm , Dbb5, Gm , Dbb5)

End with alternating between Gm and Dbb5.