Wizzard
Three Lives of Thomasina: It's been a long time since I read it, but I've got a feeling that in the original book Thomasina, The Cat Who Thought She Was God Thomasina's gender is revealed by a pregnancy ... and she's very upset that her kittens got taken away.
Edited by DaibhidC
On the website Dragon Cave (www.dragcave.net), the gender of dragon hatchlings is unknown until they are close to maturing. If you don't wait till they "gender" before naming them, you can end up giving them a gender-inappropriate name - and the names CANNOT be changed.
Also, during Christmas 2009, the special Christmas dragons (dubbed Snow Angels) were a female-only species. But due to a site glitch, the first ones to gender were male! They switched to female when the glitch was cleared up.
Edited by Moondragon007
Not sure about rabbits, but male guinea pigs have very obvious ballsacks.
Watch out where you step, or we'll be afoot.