An Odd Gesture

In this revealing and sad New Yorker article on David Foster Wallace and his unfinished novel, D. T. Max writes the following:

Doug Hesse, a colleague, made the mistake of praising an essay of Wallace’s. “He did this gesture of wiping the butt with one hand and pointing to his mouth with the other,” Hesse remembers. “I learned really really quickly not to go beyond the equivalent of ‘How’s the weather?’ ”

Clancy, I believe, knows Doug Hesse and perhaps could ask him about this, but I’m not sure what this gesture was supposed to mean, exactly. On one hand, it seems like an open invitation to punch him in the mouth; but I get the feeling that it was done with a kind of self-deprecation. I’m reasonably sure I’ve never seen anyone do this in person.