Fashion: Hi-tech
Hand Raising Nod Inflatable Bladder   (+4, -1)  [vote for, against]
Nod inflatable air bladder that raises the arm, deflated by head shake.

An air bladder fills with air and raises the weaer's arm, pressurized by constant head nodding. Head shaking releases air lowering the arm. The inflation pump is located under the chin disguised as a neck beard or oversized bow tie. The deflation valve is opened and closed by the quarter rotation of the head.
-- rcarty, Mar 11 2013

Brilliant. The vigorous nodding conveys the impression of understanding, so the professor is more likely to call on you so as to hear your insightful question.
-- ytk, Mar 11 2013

Which arm? [+]
-- pocmloc, Mar 11 2013

random, halfbakery