Here's two more:
(while sitting): close your eyes. Stick your arms straight out in front of you (like a sleepwalker). Raise your right arm up to almost straight overhead, lower your left arm until it almost touches your lap. KEEPING YOUR EYES CLOSED, bring your arms back to the same level. Open your eyes: how close did you get to level? (For lots of people, their prioperception is such that the arms FEEL level but are inches off.)
people in offices everywhere are now looking like the living dead
While standing, fold your arms. Notice which is on top, left or right. Now refold them, with the opposite arm on top.
I can do this one but - Awkward, eh?
And no I can not lick my elbow or touch my nose with my tongue