Cross your legs and idly shake one over the other. It's distracting and shows how uncomfortable you are.
Lean your body towards the door. You'll appear ready to make a mad dash for the door.
Slouch back in your seat. This will make you appear disinterested and unprepared.
Stare back blankly. This is a look people naturally adapt when they are trying to distance themselves.

Dos:

Sit up straight, and lean slightly forward in your chair. In addition to projecting interest and engagement in the interaction, aligning your body's position      to that of  the interviewer's shows admiration and agreement.
Show your enthusiasm by keeping an interested expression. Nod and make positive gestures in moderation to avoid looking like a bobble-head.
Establish a comfortable amount of personal space between you and the interviewer. Invading personal space (anything more than 20 inches) could      make the interviewer feel uncomfortable and take the focus away from your conversation.
Limit your application of colognes and perfumes. Invading aromas can arouse allergies. Being the candidate that gave the interviewer a headache isn't      going to do anything in your favor.
If you have more than one person interviewing you at once, make sure you briefly address both people with your gaze (without looking like a tennis      spectator)and return your attention to the person who has asked you a question.
Interruptions can happen. If they do, refrain from staring at your interviewer while they address their immediate business and motion your willingness      to leave if they need privacy.
Stand up and smile even if you are on a phone interview. Standing increases your level of alertness and allows you to become more engaged in the      conversation.