Muscle Tussle by Robert McKimson

6.20

Daffy Duck takes his girl to a beach, where a muscle-bound duck attracts the attentions of Daffy's fickle chick. She leaves Daffy and walks off with the hunky duck. A salesman sells Daffy a bogus strength-building tonic, and Daffy takes some, thinking it has made him into a virile power-house! He challenges the muscular duck to a series of contests involving bar-bending, chain-chewing, and weight-lifting.