“If it looks like a duck and quacks likes a duck, it's a duck, right?”

“If it looks like a duck, quacks like a duck, it's a duck!”

“You ever hear that expression 'If it looks like a duck and it quacks like a duck, it's probably a duck'?”

“if it looks like ahh duck and Quack like ahh duck then....its an afflack!”

“Gundar seemed to come to a decision. "Well, as my old mam used to say, if it looks like a duck and quacks like a duck and walks like a duck, it's probably a duck." "Very wise," Halt said. "And what exactly do your mother's words of wisdom have to do with this situation?" Gundar shrugged. "It looks like a channel. It's the right place for a channel. If I were digging one, this is where I'd dig a channel. So. . ." "So it's probably the channel?" Selethen said. Gundar grinned at him. "Either that or it's a duck.”

“If it looks like a duck, and quacks like a duck, we have at least to consider the possibility that we have a small aquatic bird of the family anatidae on our hands.”