can someone tell me what song was playing.

I watched an episode last night and it was the episode where Robin and Ted become roomies and always fight and to stop fighting they have sex, but than Barny becomes all obessive to stop the sex and then Ted stops it for him, and at the end where Ted is speaking and ther all at the car and Barnys just looking at Robin smiling, theres this song playing in the back/r..... does anyone know what its called?! ty =]