I work in Electronics sales. You can sit in on most sales presentations and find it rampant there. Nothing beats "speeds & feeds"...coupled with a presenter that has no personality (read most of them) and it's nap time.
Reminds me of a manager who used to nod off at powerpoint presentations, then spend an hour prolonging the meeting asking questions. One day he attended a meeting and only one chair was left to sit in (we all knew it was broken), he sat down and promptly nodded off. As the chair slowly descended to its lowest point, his chin hit the table top and as he he woke up pulled the lever on the chair and bolted up to the chair's highest position. He was so taken aback he never attendend another meeting again.
By the way, a finger can really hit the brain in some situations, that's why you should never pick your nose while driving. Especially considering that the distraction increases the chances of car collision, which causes the fatal finger movement.