A skillful comedian could coax a laugh with tiny indicators such as a vocal tic (Bob Hope’s “But I wanna tell ya”) or even a slight body shift. Jack E. Leonard used to punctuate jokes by slapping his stomach with his hand. One night, watching him on The Tonight Show, I noticed that several of his punch lines had been unintelligible, and the audience had actually laughed at nothing but the cue of his hand slap.