Grot "Tiger" Tank.
My grots were part of an ork waaaugh that took over an Imperial world. The Waaugh got co-opted by Ghazghull, the orks left, and there wasn't room on the ships for the grots.
The grots left behind got bored and did a demolition derby with tanks and buggies and stuff. One day they found an Imperial computer.
They figured out how to make it work, and searched for "dangerous tank," and came up with the Tiger. So they argued. Why was it dangerous? It looked okay, but could they improve on it? Then they thought, what makes it so dangerous? We should fine out. So they went back to the computer and searched Tiger (but not tank), and went "oh, that orange striped camouflage made it dangerous!"
Ork logic.

So I took one of my tiny grot tanks and painted it to look like a tiger!