What was the name of the movie about the end of the world?

In it you see all the riots and what everyone would do at the end of the world. One guy has a list of everything to do before he dies. Everyone is partying and taking drugs. Cell phones die. and at the end there is a girl and a guy on the roof top about to shoot each other at the last 10 second countdown but then the screen goes white and you never know what happened.