HEYY GUYSSSS!!!
really cool song :P

Standard tuning
Capo 3rd fret

DGive (xx0232@1)me a second I, I need to get my story straight
 Bbm
My friends are in the bathroom, getting higher than the empire state.
GMy (320003@1)lover, she's 'a waiting for me, just across the bar
      AMy (x02220@1)seat's been taken by some sunglasses, askin' 'bout a scar.

Repeat this until he says "by the time the bar closes"
               G (320003@1)            A (x02220@1)          D (xx0232@1)         A (x02220@1)    GSo (320003@1)if by the time the bar closes, and you feel like falling down

G (320003@1)             A (x02220@1)     D (xx0232@1)                  BbmI'll (x13321@1)carry, you home, tonight.........we are young........

G (320003@1)                                 A....so (x02220@1)let's set the world on fire, we can burn brighter, than the sun

(All of these chords and stuff keep the same pattern untill Janelle's part (where 
he starts doing the na na part)

D (xx0232@1)                G (320003@1)          D (xx0232@1)             A (x02220@1)"Carry me, home tonight.  Just carry me, home tonight."  (repeats)

The last part at the end is the exact same part as the "when the bar closes" progression.

Enjoy