I've heard this one a lot. The zoo I volunteer at no longer has warty pigs, but when they did I would hear this almost every time I was at the exhibit. And to be honest, this one never bothered me. It was extremely easy to see why people would think the warty pig is a warthog, as they are relatively similar species (looks wise). I've also heard:
Lemur = Monkey
Kangaroo = Dog
Spur-thigh Tortoise = Kitty
Sloth Bear = Gorilla
Red Panda = Fox
Red Panda = Lemur
Red Panda = Baby Regular Panda
Leopard = Cheetah, Jaguar, or Tiger
Serval = Baby Cheetah
Emu = Big Duck
Crowned Pigeon = Peacock
River Otter = Seal