The Big Mouth [1967] [DVD]

Hapless klutz Gerald Clamson (Jerry Lewis) is ocean fishing off the Southern California coast when he accidentally drags a scuba diver onboard his boat. The wounded diver, Gerald's doppelganger, tells him about a cache of stolen jewels secreted at a hotel on the beach. Pursued by two different gangs who both want the diamonds, as well as sexy stewardess Suzie (Susan Bay) and hotel employee Bambi (Jeannine Riley), Gerald dons a variety of false identities in an attempt to find them for himself.