At one point, Sam decides to drum up public support by kissing babies. The first baby he kisses spits and gags in disgust after Sam kisses him, but the real laughs come from when Bugs disguises himself as a baby to cause Sam trouble.
Bugs: Waaah! He bit my widdle nose! He bit my widdle nose! That bad man bit my widdle nose! [Cue Sam being beat up by a crowd of angry mothers.]
It's funnier when you realize Bugs kissed him.
Also, Sam tries the piano gag on Bugs, and it explodes on Sam so that he just tips over backward in shock, with only a shred of his mustache left, and his whole face black.