other people's habits

My coworker "M" has a slightly unusual, although not necessarily bad
habit. I'm not sure if it's conscious or simply a matter of necessity,
but every so often M closes his eyes, puts a finger over each eye and
begins to rub them vigorously side-to-side. As a second step, he then he
places his middle and ring fingers over each eye and rubs them
up-and-down. This wouldn't be such a noticeable habit except that he
does not refrain from doing this during social interactions. The other
day when we were at a restaurant, we were talking to the waitress about
her recommendations trying to figure out what to order. Suddenly the
waitress broke out in laughter and when I looked up, M was unabashedly
rubbing his eyes. The waitress must have thought this was some sort of a
joke at first, but when M entered the second, vertical stage you could
see the expression on her face change from amusement to disbelief, and
she continued to laugh, but now somewhat uncomfortably. This reminded me
of the first time I was confronted with this habit of his, so I had to
stifle my own laughter. Eventually we had all six eyes back on the menu
and sorted out our order, but now every time M does this, I am reminded
of the waitress' reaction and can hardly hide the smirk on my face. Good
thing his eyes are closed.