The 5-foot 7-inch player was appearing on Broadway in George M. Cohan's "Young America" in 1913 when matinee idol William Simpson reared back on his heels, rolled his eyes and bellowed to the gallery, "Where is Annie tonight?"
Otto Kruger dusted some imaginary lint off his sleeve, stifled a yawn and replied in a normal speaking voice, "She's outside."
Simpson was so flabbergasted at such an unorthodox delivery that he left the script and, wringing his hands, shouted at the young actor, "What did you say?"
Mr. Kruger casually stuck hand in a pocket, jingled some coins and said again in a matter-of-fact manner, "She's outside."
At that point, Cohan, who was watching the play from an orchestra seat, burst into laughter, breaking up the scene even more.
"Very soon after that," Mr. Kruger recalled during an interview in the 1960s, "the idea spread — that is, that actors could talk like people, and all of them began doing it."
Two years before Mr. Kruger gave Simpson the acting lesson — in 1911 — he made his first Hollywood movie, "Oh Pop!"
He went on to leading roles in "Treasure Island," "Thanks for the Memory," "Duel in the Sun," "High Noon," "Magnificent Obsession," "The Wonderful World of the Brothers Grimm" and, more as a lark than anything, "Sex and the Single Girl."
"For a while I played sad husbands, then I got nothing but lawyers," he once said. "Then I was a doctor, and during the war I specialized in Nazis. Lately I've been playing sugar daddies."