"The sign language of comedy"

The New York Times has a short piece on comedian Sarah Silverman, who "has earned a reputation as a sharply honed assessor of self-importance and political correctness" and who will now get her own show on Comedy Central. We are assured that she has been refining her jokes about flatulence. Glad to hear it. Perhaps she could also polish her linguistic metaphors a bit:

To those who might scoff that scatological humor should be beneath someone who aspires to poke holes in the convictions of the politically correct, she has an answer. “It’s the sign language of comedy,” she said during an interview over a lunch of poached eggs and toast at a downscale-hipster diner in Hollywood. “It’s universal.”

The sign language of comedy? What is that supposed to mean? Does she really think there's one universal sign language? Or does she just mix up gestures and sign language? In any case, I hope her jokes are better than her metaphors.