President Barack Obama drops a five dollar bill into the tip jar as he and Vice President Joe Biden, not pictured, make an unannounced visit to Ray's Hell Burger in Arlington, Va., to have lunch, Tuesday, May 5, 2009. (AP Photo/Charles Dharapak)

President Barack Obama drops a five dollar bill into the tip jar as he and Vice President Joe Biden, not pictured, make an unannounced visit to Ray's Hell Burger in Arlington, Va., to have lunch, Tuesday, May 5, 2009. (AP Photo/Charles Dharapak)