Something you probably don't even notice that you do.
Someone pointed this out about themselves. Because of the flood in Halo CE, 2 and 3, they must always have a shotgun on them whenever possible no matter what game their playing.
I just realized I do the same thing, and without a doubt this is the reason why. In every game I make sure I hold onto a shotgun because that's exactly what I always did in Halo to fight the flood.
And I bet all you Halo players do exactly the same.
I tend to rock back and forth a little bit.
Everyone points it out. I can't help it and I don't know why.
But it's fun because every chair is a rocking chair.
[spoiler]I'm lying. I know why. I was told that as an infant because there were four of us we couldn't be rocked enough by my parents so we learned to do it ourselves as soon as we could support ourselves on our hands and knees.[/spoiler]