7. Joe 'Loses' His Hand - Roman Holiday
One of the all-time great movie tricks occurs in William Wyler's Roman Holiday, as American journalist Joe (Gregory Peck) and Princess Ann (Audrey Hepburn) visit The Mouth of Truth. Peck decided to have some fun with Hepburn, placing his hand inside the mouth and pretending that it had been bitten off. The second that Peck begins to struggle, Hepburn hurriedly tries to assist him and when Peck's seen enough of her hysteria, he reveals his hand to her, at which point she bursts into laughter and the two playfully hug. It's a brilliant scene because it's so simple yet so effective; Hepburn's reaction is incredibly genuine precisely because
it is. Few actresses would be able to perform so well under pressure, whereas operating under pure instinct generates the truest - and in the case of an effervescent personality like Hepburn's, the funniest - moments.