Now here's the tough part, I hear this at work all the time and no one knows what it's called (SHOCKER!!) the only part of this song everyone remembers well enough is the intro which is like this

A calm guitar rhythm and a man with a high(ish) pitch singing or wooing like "Woo-ooo ooo ooo" it reminds me of Adam Lavigne but I don't think it is him... this intro part is almost the base of this song it comes in after the chorus and also ends the song

If I were to ferther explain the singing it would be like

--------^^^^--------____
Woo ooo ooo ooo

With

- being your starting tone
^ being a few pitches up
- back to your starting tone
_ a slight pitch down

If you have a guitar it would be like this as the vocal pattern

e|--0--7--4--2--|

With each note falling on a beat

I don't expect an answer right away I just hope I can figure this out