Not a crocodile, but not an alligator. A
little of both. Kind of
like Patty Duke performing both Patty and Cathy on the Patty Duke show. Well, not really, as they were both the same person, and a croc and a gator are not the same
animal. Still, the term is useful when a huge reptile is about to eat you and you can't distinguish between the two.
You: Help! A big reptile is about to
eat me!
Someone else: What kind of big reptile
You: I don't know, maybe it is a crocodile, and maybe it is an alligator!
Someone else: You
will have to be more specific!
You: Arrrrrghhhhh, I am being eaten
alive by a crocogator!
Someone else: Aha, now I understand!