In Emery Hawkin's animation, Daffy Duck here moves very fluidly, and noticeably a little skinnier. Hawkins uses his thing with the eyes here in this clip from the great WHAT MAKES DAFFY DUCK (1948).

Notice how he's able to use the same technique to convey different emotions. With Daffy it's to signify lust and perversion, while with the fox it's to express shock and confusion.