Comet Ping Pong, the Washington, D.C. pizzeria that internet hoaxers made famous as part of the "Pizzagate" conspiracy theory, was the alleged victim of arson on Thursday night, and investigators are searching for a suspect.   The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) sent out a tweet Friday night with a picture of a "white male, 25 - 30 years old, with blonde hair, mustache and a beard" saying that the man was "wanted for questioning."   According to the Washington Post, an unidentified patron set fire to a curtain in the back of Comet Ping Pong on Thursday evening. The fire was extinguished by staffers and no one was injured.   Because investigators found burned matches and a bottle of charcoal lighter fluid, investigators made the "unanimous" decision that the fire was caused by arson, according to the Post's reporting. ATF is seeking the pictured