In military slang, "oh dark thirty" or "zero dark thirty" means "the middle of the night", or some time you'd rather be asleep. As in, you're answering the question "What time do you have to wake up?" with "Dark." I replaced the "zero" with "zebra", because this is some kind of army-commando-zebra-girl thing. I imagine she's either the occasional-companion or mortal enemy of Lazerhorse.
Looking at the thumbnail, the head could stand to be a little smaller, and the arms and legs could be a little longer. But it's mostly okay.