Lizards and
snakes possess two penises, which when not being used in the act of
copulation are retracted into the
cloaca. In scientific parlance, each of these is known as a
hemipenis.
It is difficult to determine the sex of reptiles, but skilled handlers are able to do this by pressing upon the cloaca in such a way as to evert the hemipenes, if they are present. Do not try this without the guidance of a professional, as you may injure your pet.