These are some habitual mannerisms that other people brought to my attention that I had.
When I'm at a store or something, and someone asks if I want the receipt, I always say "Naaahhhhhh." Drawn out just like that. All the time.
When I'm at a restaurant, and I'm deciding what to drink, this is how it usually goes:
Me: "Do you have raspberry iced tea?"
Them: yes/no
Me: "Do you have root beer?"
Them: yes/no
Me: "Do you have Sprite?"
Them: yes/no
Me: "I'll have a Dr. Pepper."
If someone asks me if I want something, I'll wait a few seconds and give a very authoritative "No" in reply. Apparently this is hilarious to my friends, who laugh every time it happens. Not sure why.
When I'm at a restaurant, I take off my shoes while I'm eating. Just feels more comfortable.
When I'm eating out with people, and we eat in a booth, I always end up laying down on my side of the booth or lounging. Always.
When I see something happen that I think is stupid or something's annoying me, I'll put my hand like this:
(not my hand)
Raise it up about 90 degrees, and bring it down again really fast and point it in the direction that's causing me to do it. If it's a person, I'll say "This guy." even if it's a girl.