Hey, thought I'd list some of the scary things to happen in halo when your playing with your friends. Feel free to add or subtract from the list.

5.going for the rocket launcher, and it's already gone.
4.When playing boarding action(team sniper) you hear someone call out your level number and color.
3.Going for the invisibilty and it's already gone.
2.Walking down a hallway and hearing "tink, tink,tink"
1. Getting close to someone so you can hit them from behind, and all you see is a smoke trail, and the other person fall.