A neutron walks into a bar, orders a beer, and pulls out some cash to pay. But the bartender won’t accept the money. “For you,” he says, “no charge.” If you think that’s funny, wait’ll you hear the one about the muons. On January 13, the tiny New Deal Caf in Greenbelt, Maryland, will resound with such one-liners, as well as physics-themed poetry, music and dramatic readings. James Riordon, the public affairs officer for the American Physical Society, decided to host an open-mic night to kick off 2005, the 100th anniversary of E=mc2 and several other of Albert Einstein’s greatest hits from 1905. Physicists have tried their unique brand of wit at the New Deal before, with mixed results. Occasionally the crowd gets the humor, but, Riordon says, “sometimes they laugh because it’s a nerd telling an incredibly nerdy joke.”