CASH AND CARRY (1937)
Found this online, someone paused it at just the right moment when Curly burnt his finger and sucked on his finger, but since he paused it, Curly gives you the finger.
Actually, he was chewing gum, and was using his finger to pop bubbles in his mouth.
Happy birthday to Jerome Lester Horowitz, aka Curly Howard. He would have been 109 today.